How Ant Colonies Get Things Done

How Ant Colonies Get Things Done

>>GORDON: So I study ants and I study ants
because I’m interested in how complex systems work. So ants always live in colonies and
colonies always consist of one or more reproductive females who just lay the eggs and then the
ants–all you see walking around are sterile female workers. And the queen doesn’t tell
anybody what to do, doesn’t give any orders, nobody directs the behavior of other ants,
and so the question that fascinates me is then, how is it possible for an ant colony
to accomplish everything that it does and how is it possible that ants are such a successful
group? There are 12,000 species. There are ants everywhere on earth; clearly they’re
doing something right. So I want to tell you today about work that I do in the desert in
Southeastern Arizona very near to the Mexican border, near the New Mexico State Line. This
is my study site. And that’s a rabbit, not an ant. And I’ve been working there now following
the same population of colonies since 1985, and the ants that I study there are called
Red Harvester Ants. The species name is Pogonomyrmex barbatus. And this is a nest of a mature colony.
So you see in the middle, the nest entrance. And these ants are called harvester ants because
they forage for seeds on a trail that they sometimes clear, sometimes not, through the
vegetation that might go about 20 meters away from the nest and they bring the seeds back
and store them inside the nest. This mound is about a meter wide in a mature colony.
So every year since 1985, I have mapped all the colonies on the site. This is a map from–this
happens to be ’93, so the site is not that big. It’s about 250 meters by about 400 meters.
There’s a road. The boundaries are arbitrary and every one of these little filled squares
is an ant colony. Every colony has its name which is a number and every year I go back
and find all the colonies that were there the year before, figure out which ones died
and put the new ones on the map. And by doing that, I’ve been able to track colonies through
their life cycles as the colony gets older and larger. And because that development of
an ant colony is important for the story I want to tell you, I want to now start and
take you through the life cycle of an ant colony. So, ants don’t make more ants. An
ant colony is not a population; it’s actually a collection of sisters. But colonies make
more colonies and the way they do that, in this species as in many ant species, is it–is
in an annual mating flight were all of the colonies in a population of colonies send
out the winged reproductives. This is a male with wings, this is a female, virgin female
with wings. And in these ants, as in most ants, you can tell the difference between
males and females because the male–the males have tiny heads and the females have much
smaller–much larger heads. And that’s because the males live only for a couple of weeks;
they don’t live long enough to eat and so they don’t have much jaw musculature. So,
they don’t need a head for what they do which is just to mate. So there’s a male on his
way to the mating flight and there is a queen, still has her wings and she’s mating. That’s
her abdomen and she’s mating with this male, that’s his abdomen, his thorax, his head.
And there’s another male on top waiting his turn. And we’ve recently understood that because
of the strange genetic system in this particular species, a queen has to mate at least twice
and they often mate many times. So after they mate, the males all die. And they’re mostly
dead by the next morning, they’re kind of clustered underneath the bushes, trying to
get out of the sun. And the queens, the newly mated queens, fly off apparently at random,
drop their wings, dig a hole, go into that hole and start laying eggs. And in this species,
the queen will lay eggs using sperm from that original mating for 20 or 25 years and she’ll
never come out again. So here’s a picture from my book, “Ants At Work,” showing the
queen digging her hole on that first day after she mated and here’s a real hole. They go
down about 18 inches the first day. They get down there, lay the first batch of eggs, takes
about six weeks for them to develop and once they develop, the workers do everything for
the queen. She feeds that first batch of larvae by regurgitating from her fat reserves and
then she never goes out again. So here’s what a one-year-old nest looks like. This hole
here is the nest entrance and there’s a pencil for scale and here’s the rock that names this
colony. So these workers, these ants walking around, are ants that are produced by the
queen who mated the previous summer. It’s a one-year-old colony. And here is a three-year-old
colony, so here’s the nest entrance, there. There’s the hole for the nest entrance. There’s
a pencil for scale. Even–by the time the colony is three years old, they’ve started
to cover the nest mound with little bits of rock. And here is a five-year-old colony and
there is the nest entrance, and here’s a pencil for scale. It gets to be about a meter across
and that’s about as big they get by the time the colony is five years old. So this is what
colony size in thousands of workers looks like as a function of colony age in years.
So it begins with zero ants, just the founding queen, and she goes on laying eggs year after
year, growing very quickly through years three and four until about year five when the colony
gets to a stable size of 10,000 to 12,000 ants and it stays at that size for the rest
of the colony’s life. Eventually, when the queen dies, there’s nobody to produce more
ants. And although the ants live for maybe another year, once the queen has died, eventually
the colony will die. And it’s at this point where the colony reaches its stable mature
size that it first begins to reproduce, that is to send out winged ants to the population’s
annual mating flight. So I know how colony size changes as a function of colony age by
digging up colonies of known age and counting all the ants. And it’s hard to dig a hole
in the desert, so we get a backhoe to dig a trench next to the nest. Here is a nest
and there I am standing in the trench. I ‘m wearing gloves because these ants have a really
powerful sting. That’s Stephen Cover who’s at Museum of Comparative Zoology at Harvard
and has a wonderful x-ray sense for finding the queen which is really important, because
unless you find the queen, you don’t know that you’ve found all the ants. That was a
more recent version; we dug up a colony that had just moved. So here’s what it looks like
underneath. This is the ground, here’s a trowel for scale. And we find the whole mass of chambers
surrounding the nest entrance and that goes down–it’s kind of cone shaped and it goes
down about as deep as the mound is wide. And then there’s another tunnel which might go
down another meter or so which leads to a small chamber and that’s where we find the
queen and all brood have gone to escape the backhoe and us. So this is–the flag shows–this
a nest that we kind of sliced down the middle, and the flag shows where the nest entrance
was and you can see that most of the chambers are around the nest entrance. And inside the
nest we find the seeds that the ants store, they prefer grass seeds. Here’s another picture
of a tidier chamber and often we find the seeds are piled up very methodically, here
are the small ones underneath and then these larger ones. Here’s an ant for scale. And
also inside we find the brood. So ants, like all insects, begin as eggs and then they turn
into larvae, look like maybe little caterpillars. And it’s the larvae who do most of the eating,
so most of the food that an ant colony takes in is actually consumed by the larvae. And
after the ants are larvae, they become pupae which corresponds to the cocoon of a butterfly.
And when the–when the pupa is mature, then workers come along and slice it open and the
ant comes out as an adult. Those are the ants that we see walking around. And once the ant
emerges as an adult, it doesn’t grow anymore. So the process that I think about is what
I call task allocation. And that’s the question of how, without any central control, any management,
any direction, how the colony gets the right numbers of ants to perform each task as conditions
are changing. So things happen to an ant colony, this is what the site looks like after the
summer rains. And I think this is probably the function of the escape tunnel, not really
to get away from me and my backhoe but instead to have a place to go when the ground floods.
And after the ground floods, there’s a lot of damage to the nest, so the colony has to
put extra effort into fixing the nest, into nest repair. And this is true for all of the
different activities that a colony performs. It has to adjust the numbers performing them.
Now I divide the activities that I see outside the nest into these four categories: foraging;
collecting food; patrolling, that’s supposed to be a magnifying glass because the patrollers
search early in the morning; nest maintenance, taking–building and taking care of the chambers
inside the nest; and midden work, dealing with the refuse pile or midden. And the first
thing you need to know about these different tasks is that the ants performing these different
tasks are all the same size. So you may have seen some species of ants, actually the minority
of ant species, in which the ants, the workers come in different sizes. But in this species,
as in most ants, the workers are all the same size so you can’t tell what an ant is doing
by just looking at it. So I want to show you this film that illustrates these four different
tasks. Starting with the foragers, so the foragers leave the nest and they go out in
streams which we call trails, although they’re not very distinct trails–and I’ll show you
some picture soon–they’re more like–sometimes they look more like big blobs. They go out
and they get to a certain point, they search around and then they come back carrying whatever
they found. As soon as they find a seed or if they’re really lucky, a termite, they bring
it directly back to the nest. So what you’ll see here is an ant–some ants carrying seeds
going directly back. And the film is streaming really fast. I don’t know quite why but you
might catch a glimpse of an ant carrying a seed.
>>This is not real time?>>GORDON: Well, the film is moving faster
than it is in real time but the film is moving fast for some reason. Okay. The next activity
is one that I’ll tell you a lot more about, the one I call patrolling. So the patrollers
go out early in the morning and they walk around, not that fast, and they touch the
ground with their antennae. So ants smell with their antennae. These ants, like most
ants, don’t see. So their universe is mostly olfactory, it’s mostly about smell. And they
sometimes stop and touch antennae with other patrollers that they meet and they walk in
this characteristic zigzag trajectory. And then after a while, they just go back into
the nest. They don’t collect anything, they don’t do anything else, they go out, they
smell around, they go back in and the foragers will not go out until the patrollers come
back. The next activity is nest maintenance. So the nest maintenance workers work mostly
inside the nest and they line the walls of the chambers with moist soil and it dries
to a beautiful adobe finish so that the ceiling and the floor of the chamber is lined with
adobe. And then they bring out–like these ants, they bring out the dry soil and put
it down. They also bring out the garbage and put it down on the midden or refuse pile.
So you see nest maintenance workers outside the nest only occasionally, coming out carrying
something in their mandibles, putting it down a few inches outside the nest entrance and
going back in. So they’re all mixed up in the stream of other ants and all they do is
carry stuff out and they go back in. Then the midden workers work on the refuse pile
which contains the husks of the seeds that ants eat and also these little pebbles that
they collect. And what you see a midden worker doing is like this one, just picking up some
little piece of garbage and turning it over and over in its mandibles. And we’ve recently
understood that the ants are putting in a colony specific odor into this stuff. They
collect especially porous stones because it’s a good receptacle for their chemicals and
they move it back and forth across the mound. They pile it one day here, another day there,
then they move it back. So these ants, the foragers, the patrollers, the nest maintenance
workers and the midden workers are only the 25% of the colony that works outside the nest.
And once an ant starts working outside the nest, it comes in and out and into these chambers
just inside the nest entrance but it never goes back down deeper. So ants start out–we
think that probably the youngest ants work inside the nest with–in brood care, feeding
the larvae and taking care of the larvae. Then they’re–when ants that are working outside
bring food in and put it down, then–they just put it down just inside the nest entrance
and other ants come up from underneath, collect the food, and carry it back down again, and
then they store and process the seeds. Then the nest maintenance workers are working to
line the walls of the chambers and to carry the dry soil back out. And then the queen
does nothing really but lay eggs. So even if she had the intelligence to somehow direct
the behavior of the ants outside the nest, keeping in mind that the ants don’t see, there’s
no way that the chemical information could get through this whole mass of chambers to
the ants outside the nest in time to tell them what to do. Then there’s this escape
tunnel but we don’t think that the queen spends much time there except when somebody is digging
up the nest. Then one of the really surprising things about this is that there seems to be
a large group of ants who are basically doing nothing, who you could think of as reserves
in the sense that if something important would happen, they would go back out and help. But
in my now almost 25 years of watching these ants, I’ve never seen anything that brings
out most of the ants. So whatever it is, if they’re reserves, I’ve just never seen it
happen or maybe they really are ants that just do nothing. And one of the interesting
questions about the network of interactions that I’m going to be telling you about is
whether this group of basically inert ants has some function that helps regulate the
whole network. Did you have a question?>>[INDISTINCT] I know because I’ve seen ants
doing one function. They’re not stopping for other functions. So is it, you know, like
tagging them?>>GORDON: Yes, I’ll show you some pictures.
The question is how do I know which ant is doing what? And I’ll show you that in a minute.
So when I started out working on this question of task allocation, the question I started
out with was, “Are these different activities interdependent? Does it matter to one group
of ants what another group is doing?” And so I did a series of experiments in which
I changed the numbers performing one task and looked to see how that would affect the
numbers performing another task. So for example, we’ve put out piles of toothpicks right near
the nest entrance early in the morning when the nest maintenance workers were active and
the nest maintenance workers carry the toothpicks away and it took extra nest maintenance workers
to do that. And I wanted to see if extra nest maintenance work would have an effect on the
other tasks. And then we repeated these experiments using marked ants, we used to mark them with
model airplane paint. It has to be hot fuel proof model airplane paint with these ants
and you could mark them according to task. And now we used a little bit more high tech
Japanese marker but same idea. And we did this with ants that were marked according
to tasks. So these are all blue nest maintenance workers and here’s a yellow patroller and
somewhere in here, there’s a green forager which maybe you can see. I can’t see right
now. So the results of these experiments were that, yes, the numbers performing one task
do affect the numbers performing another task. So the different groups are not working autonomously.
For example, if I make a mess that the nest maintenance workers have to clean up, the
foragers stay inside the nest. They become less likely to forage. And that was true for
all the pair-wise combinations of activities. And the next result was that ants actually
switch tasks. So for example, if I put out extra food, then the patrollers will stop
patrolling and go to collect the food. The nest maintenance workers will stop doing nest
maintenance work and they’ll go to collect the food. The midden workers will stop doing
midden work and they’ll go to collect the food. But not all transitions are possible.
And this is how it works, that when more ants are needed to forage, like I just showed you,
the patrollers will switch to forage, the midden–the patrollers will switch to forage,
the midden workers will switch the forage, the nest maintenance workers will switch to
forage. And when more patrollers are needed–and I created a need for more patrollers by creating
disturbances that recruited out more patrollers. If more patrollers are needed, then the nest
maintenance workers will switch to patrol. But if more nest maintenance workers are needed,
so for example, I make a mess that requires more nest maintenance workers to clean up,
nobody will switch back to do nest maintenance and they have to get more nest maintenance
workers from the younger ants inside the nest. So, foraging is kind of a sync and all the
other activities flow into foraging and once an ant becomes a forager, it never goes back.
And once I understood that, that meant that each ant must be making moment to moment decisions
not only about which task group it belongs to, not just, “Am I forager or am I a nest
maintenance worker?” but whether to be active right now. That is if “I’m–given that I’m
a forager, should I go out forge right now?” When I first saw the results, I had thought
it was possible that the reason that, when I recruited extra nest maintenance workers,
I got fewer foragers is that the nest maintenance work–that the extra nest maintenance workers
were foragers that had switched over. But once I understood that once an ant becomes
a forager, it never goes back to nest maintenance, that made me realize that what must be happening
is that when extra ants are doing nest maintenance, that affects the decisions of foragers whether
to be active. So it’s not the same ants switching over but each ant is making moment to moment
decisions about what to do. And the most puzzling result of these experiments was the task allocation
seems to be related to colony age. So it’s related in this way that older colonies are
more consistent and more homeostatic in their response to perturbations while younger colonies
are more variable where, by more consistent, I mean that if you take a group of older colonies
and you perturb them or create a need for more work in some particular task group, do
the same experiment over and over, you get the same result from different groups of older
colonies. Whereas with younger colonies, a group of younger colonies will all respond
one way this week and another way next week. That is the variance within colonies, among
colonies in a given week is not any different from older colonies and younger colonies but
as a group, all the younger colonies will do one thing this week and they’ll all do
something else next week, which suggests that the younger colonies, the smaller ones are
much more sensitive to whatever is different between this week and next week. And the other
difference is that the older colonies are more homeostatic. So as I ramped up the magnitude
of the perturbations, the worse it gets, the more an older colony will just leave everything
else aside and concentrate on foraging so that the greater the magnitude of the perturbation,
the more an older colony resembles an undisturbed colony. Whereas in a younger colony, the greater
the magnitude of the perturbation, the greater the magnitude of the response. And what’s
surprising about this is that an ant lives only a year. I’ve lost my pointer so–you
see, the lifespan of an ant is only a year. So that means that the response of the older
colonies, while it’s clearly different is not the response of “Why is there more experienced
ants?” because the ants in the older colony are not any older than the ants in the younger
colony. So something else about the organization is changing. Yes?
>>As new ants are born, do you–they go back to the baseline number of foragers and other
other roles? And do new ants take on the role that the dying ants leaving behind or do they
fill that up [INDISTINCT] that time?>>GORDON: Well, the flow is from the ants–so
the question is do new ants take on the role on the dying foragers? No, there’s a sequence
and the new ants start at the beginning inside the nest and are recruited up into the pool
of ants working outside gradually. So a new ant is in a different position in that stream
than the dying forager.>>So I guess my last one is if you put out
lots of food and cause a huge influx of foragers, over time as all those foragers die, does
it get back–does the nest get back to having a small number of foragers?
>>GORDON: Yes. So the question is over time, if new ants are recruited into foraging, will
the numbers go back down? And the answer is yes, they will. Yes?
>>So you say there’s a sequence. Can you manipulate the speed at which they move through
the sequence?>>GORDON: Can you manipulate the speed at
which they move through the sequence? Yes. If you create a need for more ants doing one
task, you pull them out of the previous step into the next step. So–well, to go back here,
so clearly something about the organization is changing as the colony gets older and larger.
And since it’s not the experience of individual ants, an obvious place to look is in the size
of the system because the obvious thing that’s changing is that the older colony is larger
than the younger colony. And so that’s where it got me started thinking about what kind
of ant decision rules could explain these outcomes? And we know that the ants’ decisions
must be based in part on just what they encounter in their environment as they’re walking around,
otherwise, there would be no ants at picnics if they couldn’t notice the picnic. But it
must also be based on their interactions with each other or it wouldn’t make any difference
to the foragers what the nest maintenance workers are doing and so on. So I’m looking
for decision rules that are in part based on interaction and I started to explore the
idea that ants use simply the rate at which they interact to decide what to do. So the
idea is, “Okay, I’m a forager, I expect to meet a forager every so often and if I do,
my probability of going out to forage stays the same. But if the rate at which I meet
other foragers goes down, I become less likely to forage.” And that–in that way, each ant
doesn’t need to understand what’s happening, nobody needs to make any global assessments.
Each ant just uses its own experience of its interactions with others to decide what to
do, but in the aggregate, you would see the task allocation that we see. And you might
expect such a system to operate very differently when the colony is large from when the colony
is small because if the ants have the same algorithm, the same thresholds in a small
colony and a large colony, their experience, the rate at which they meet others, would
change because in a large colony there’s more other ants to meet. So, if ants are going
to use the rate at which they interact to decide what to do, they have to know who they’re
meeting. So you might wonder, well, how does an ant know the difference between meeting
a forager or a nest maintenance worker? This is work I did with Dianne Wagner who was a
post doc at my lab. And we found that ants within a colony differ in smell. So it’s well
known in social insects that all social insects, like many other insects, are covered basically
with a layer of grease. These are long chained fatty acids or hydrocarbons. And that’s how
an ant or a bee or a wasp knows if another one is a nest mate because they have a colony
specific odor. And what we found is that they also, within a colony, differ in odor according
to task. And in particular, the ants that spend more time outside, the foragers, shown
with the white bars and the hatched bars, the foragers and the patrollers, have more
n-Alkanes in their cuticular hydrocarbons whereas the ants that are inside smell different.
And then we did an experiment in which we took ants, nest maintenance workers that had
mostly been inside the nest and we exposed them to the same conditions that foragers
and patrollers experience outside the nest, namely high temperatures and low humidity,
and we got those increases in n-Alkanes. So it’s what they do that makes them smell different,
in the same way that a carpenter might get a callus on our hands, an ant as she’s walking
around outside comes to smell different. So the smell doesn’t make them do something different,
it’s because they’re doing something different that they have a different hydrocarbon profile.
So I want to tell you about how the system works in particular with respect to foraging.
So here’s a picnic, as everybody knows, where there’s ants, there will be a picnic–where
there–sorry, where there’s a picnic, there will be ants. It doesn’t work the other way
as far as we know. So that’s a great example of the regulation of foraging activity, that
is how is it that the colony decides, first of all, whether to forage it all, second,
where to go, like where to go–where the picnic is, and finally, how many foragers to send
there. So I want to talk to you now about the details of the regulation of foraging
in harvester ants and to do that, I want to tell you about the particular challenge for
Harvester ants in the network that controls foraging. So, first of all, Harvester ants
compete with their neighbors of the same species and it works like this. This is a picture
of the foraging trails of one colony. So here’s the nest entrance, this is about ten meters
across here, and you can see that sometimes they go out in a kind of a line that looks
like a trail, sometimes they go out in a line that turns into a big blob, sometimes they
just spread out. And from day to day, a colony will go in different directions and sometimes
the trails of neighboring colonies meet. So now, this is the entrance of one colony, this
is its neighbor and sometimes they happen to overlap and when they overlap, either one
colony’s forager gets the seeds or the other colony’s foragers gets the seeds. And sometimes
they fight. So here’s a picture from my book of an ant of one colony grabs the petiole,
that’s the segment between the thorax and the abdomen, with its mandibles and they kind
of tumble around for a while. And sometimes they just won’t give up and so the ant that
has grabbed on eventually dies from desiccation because these ants can’t be outside in the
heat, in the desert very long. And the muscles of the jaws are so strong that they remain
clenched even after the ant dies, the rest of the ant breaks off and the ant that was
attacked walks around for the rest of its life with the head of another ant clamped
on. So the cost in overlap is mainly in competition for food but also in the cost of fighting.
And over time, just as trees in a forest compete for light and it’s hard for a young, small
tree to get started near a large old one, so in this population, by looking at the census
data, over time we can see that new colonies are unlikely to survive near old, large ones.
So the main premise of their foraging, regulation of foraging has to do with competition for
neighbors–with neighbors. So the next thing is that these ants have to spend water to
get water. That is they store seeds and the foraging, going out in the hot sun, costs
water because the ant dries out while it’s foraging, and they get their water from metabolizing
the fats out of seeds. So their foraging system seems to be based on the premise that its
not worth foraging, its not worth going out to look when the search time is long, when
there’s not–food isn’t available and you have to spend a lot of time outside looking
for food. So it’s not worth it to use up a lot of water to get in water. And the way
that the food is distributed is patchy and also ephemeral, the distribution changes all
the time. So, they forage for seeds and they collect seeds that are mostly distributed
by wind and by flooding, not by–not from nearby vegetation. So it’s not the case that
certain places out there are good, reliable sources of seeds and other places aren’t.
Anywhere is just as good as anywhere else basically, there might be local patches but
they’re unpredictable. And so, anytime that one colony searches an area, it has pretty
much as good a chance of getting seeds as its neighbor. And the final thing is that
search time is a good measure of availability of food and that’s because of the way that
a foraging trip is set up. So an ant leaves the nest, a forager leaves the nest, it goes
out for a while on the trail and then it leaves the trail and spends a lot of time searching
around and eventually, as soon as it finds something, it picks it up and goes right back
to the nest. So it goes maybe 20 meters from the nest with an average time of about 20
meters. And Blair Beverly who was an undergraduate who did great work with me but instead of
going to grad school, he came to work at Google, he did a wonderful honors thesis in which
he showed that trip duration is clearly correlated with search time. How long the ant spends
outside is correlated very highly with how long it has to spend searching and it’s not
very–it’s not correlated at all with how long it’s spent traveling. So they walk so
fast to the place that they then leave to search from that the time they have to spend
searching is a really good measure of how long they’re going to spend outside. So, the
idea is that the more food there is out there, the more available food is today, the less
you have to search and the quicker you come back. And it seems as though that’s pretty
much the same everywhere on a given day, because what determines food availability is more
whether it’s rained recently and washed up the dirt off the seeds than anything special
about a particular patch. So, here’s how they regulate foraging given those constraints.
The patrollers come out first, this is the hardest part for undergrads about working
with me in the desert is that if you want to deal with the patrollers, you have to get
up at 4:30 in the morning because they come out right as the sun comes up. And they’re
the gate keepers. They tell the foragers whether to go and which way to go. So the foragers
don’t go out, as I said, until the patrollers come back so it’s the return of the patrollers
that signals the foragers that it’s okay to go out. And I want to tell you about a field
experiment that we did that showed how this works. Taking advantage of this fact, we knew
that the foragers would not go out if the patrollers don’t return, so we could collect
up the patrollers as they’re coming back, put them in a little box and know that the
foragers would not go out. So here’s a picture of a couple of students collecting up the
patrollers as they come back. And this is work I did with Mike Greene who’s at the University
of Colorado at Denver. And we did a field experiment that–in which we removed the patrollers,
so we put the patrollers in a box so they wouldn’t go back, and then we dropped into
the nest little glass beads that were coated with the extract of the cuticular hydrocarbons
of the patrollers. It’s a little glass beads that smelled like patrollers. And here’s a
picture of the glass beads and that was enough to bring the foragers out. So this shows the
number of foragers in response to live patrollers, that’s the control, and then two different
extracts of patroller hydrocarbons, the full lipid extract, and then the hydrocarbons which
are part of the lipid extract. And you can see that little glass beads that smell like
patrollers coming into the nest were enough to bring them out foraging, whereas little
glass beads that just had the solvent pentane as a control or glass beads that smelled like
another kind of ant, the nest maintenance workers, didn’t bring out the foragers. So
this is how we know that ants are using just the–just interactions with each other and,
in particular, the smell of the other ants to decide whether to go out or not. And it
turns out that the onset of foraging depends not just on having patrollers come back but
having patrollers come back at the right rate. So we tried dropping in the glass beads at
different intervals. One bead every hundred and eighty seconds, every forty five seconds,
and it’s only when they come back at a rate of one bead per ten seconds that the foragers
will go out. So this shows the foraging response. There’s also a foraging response if the beads
are dropped in pretty quickly but if they’re drooped in too quickly, it’s not as good as
dropping in it the right rate. And of course, we got the ten seconds by measuring the rate
at which patrollers are usually going back at the time that they come out to forage.
So it means that the foragers inside the nest are using the rate at which they encounter
something that smells like a patroller, not anything the patroller does, not anything
the patroller tells them, simply the rate at which patrollers come back to decide to
go out. So it seems that for the foragers, the fact that the patrollers can go out and
come back is enough to guarantee that it’s safe to go out and try to forage. So, actually,
we were able to make the foragers come out sooner by putting in the patroller beads sooner
at the right rate. So it suggests that what’s happening to the ant is simply something like
this, some kind of threshold where the ant, when it experiences an encounter with a certain
kind of ant, it has a response that has a decay. And if it gets enough encounters often
enough, its response is pushed over some threshold and its probability, say of going out to forage,
increases enough that they’re likely to go out to forage. But if the encounter happens
much, much later then by that time, since this decay seems to be on the order of about
ten seconds, the ant has forgotten that anything ever happened to it and the process has to
start over to make it go out. So we don’t know that that’s how it works but this is
how we think it works. The patrollers are also telling the foragers which way to go
and we figured this out in some experiments in which we blocked off different trails.
So this is a nest with–here’s the nest entrance and there are four foraging trails and the
entrance to the opening in the grass to the foraging trails which extend out for another
20 meters or so is marked with a pair of white flags. So it goes through here, through here
and so on and we took this foraging trail and we blocked off the entrance so that the
patrollers couldn’t get on there. And if we kept the patrollers from going on that little
segment of the trail which is maybe 20 or 30 centimeters, just on the nest mound, then
the foragers didn’t go there. The foragers didn’t choose that trail that day. And so
then we kept the patrollers from the mound and we put down extract of different glands
inside the ant, the Dufour’s gland, the poison gland and the solvent. And the Dufour’s gland
was enough to get them out there. So we found that the ants are telling the other–telling
the foragers which way to go but they’re only directing them which–towards a certain compass
direction but they’re not directing them towards any particular food source. So the patrollers
are saying, “Okay, it’s safe to go out because we came back and it’s okay to go this way,”
and it seems as though the decision of the patrollers isn’t based really on anything
to do with food quality but only that if the foragers–the patrollers go out in the direction
that the foragers went the day before and if they meet the patrollers from the neighbor,
then they don’t choose that direction. So the patrollers are likely to avoid the directions
in which they met the patrollers of the neighbor and they’re are also–so if you can go out,
you can come back fast enough and you don’t meet anybody from the neighbor, then that
direction is okay and that’s the direction that the foragers take. So–yes?
>>How they found out the direction of the road? I mean, when they come back, how do
they pass the information and the direction they’re given?
>>GORDON: By putting down this chemical on the mound. So they don’t come back–if they
meet the patrollers of the neighbor, they–we think this is what happens, if they meet the
patrollers of the neighbor, they are less likely to take that way back. What we know
is that if they–the more patrollers come back in a certain direction, the more likely
the foragers are to use it and that’s because the patrollers, whenever they come back, they
just put down some chemical. So, if there’s any process that makes the patrollers less
likely to come back in a certain direction, it will make the foragers less likely to use
that direction. But they’re not really giving the foragers any information about what’s
good or bad about that direction. So, they are only saying, “Okay, we went out. This
the way we came back. It’s okay to go out.” So, they tell the foragers whether to go at
all and which way to go. Now, what determines how many foragers go? So, it turns out that
this is a second process that depends on the rate at which they interact, and here it’s
not interaction between the patrollers and the foragers, it’s interaction between the
foragers that have just come back from a trip and other foragers that are coming in with
food. And the way we figured this out was to take away foragers returning, first foragers
returning with food and then foragers–unsuccessful foragers. And if you take away foragers that
are coming back with nothing, it has no effect. But if you take away foragers coming back
with food, it slows down the rate at which more foragers go out. So, the foragers go
out on their first trip because of the patrollers, they come back and then the probability that
they go out again simply depends on the rate at which more foragers come back. So, this
makes sense from the perspective of the colony because the rate at which foragers return
is a measure of the availability of food. So, the more food there is out there, the
more quickly the foragers are going to come back because they won’t have to search so
long. So, for a forager inside the nest, the rate at which foragers are coming back is
a measure of whether it’s a good day to forage. So they don’t have to know anything about
that rate, they only have to respond to successful foragers coming back. And we found that they
respond really surprisingly quickly. So, here is the cumulative forager outflow in one colony
on a particular day and this is the same thing per 10 seconds, so these are the same data.
And at this interval, we started to collect for two minutes the ants returning with food.
And you can see that within just a couple of minutes, the rate at which the foragers
go out again starts to slow down. So they respond within minutes to a very small change
in the rate at which foragers are going in. They’re really surprisingly sensitive to fluctuations
in the rate at which foragers are coming back. So, returning foragers removed for three minutes
immediately lead to a change, a decrease in the rate of forager return. So, this was surprising
to me because after all, what they’re collecting is seeds. The seeds are not going to go anywhere
in two minutes. So, these are not like the opportunistic ants that you see in your kitchen
around here, like the second that you drop a crumb on their kitchen counter, the ants
are there. These ants are foraging for resources that just stay on the ground until somebody
finds them. And so it’s really surprising to me that they have such a fine-tuned system
that responds so quickly to changes in the rate of forager return. And I think that it
may simply be a function of the decay rate in their memory. That is if foragers can only
remember something for about ten seconds, then they can only respond to something that
happened very recently so that this very quick adjustment of forager return rate is actually
a by-product of the memory, the decay in memory. So, the fact though that it is so fine-tuned
means that they can actually adjust forager outflow very well to food availability, that
is when it takes a long time for ants to find food, then that decreases the rate at which
ants go out and they can adjust quite carefully to forager–to food availability. Now what
determines where the foragers go, remember that the patrollers are just directing them
out in a certain direction. Another thing that—-so a forager comes out of the nest
and takes one of the trails that the colony is using that day and then goes off somewhere
to search for seeds. And the other thing that Blair Beverly found out is that each forager
is returning over and over to the same location on successive trips so the forager leaves
the nest and goes out somewhere. And what he did was to mark ants individually, so we
had a three-color system, you know, a different color on head, thorax, and abdomen. Actually,
six-color system but three paces to mark. And so he could follow individual ants and
found that the destinations–the different destinations of different trips for the same
ants was within about half a meter. So the ant then, for the perspective of the forager,
the ant goes out first thing in the morning when the patrollers come back at a certain
rate, it goes out, it finds a certain place and then it goes back to the nest once it’s
found something and then it waits to go out until it encounters ants returning at a certain
rate. Then it goes out again, it goes out back to the same place over and over throughout
the day. And what this means is that from the perspective of the colony, the return
of foragers from one direction is stimulating more foragers in another. That is there might
be ant number one who’s going back and forth to here all day and ant number two is going
back in forth to there all day but the return of this ant from foraging here is going to
stimulate an ant to go out over there. And so this system only works in a situation like
this one where the food is distributed pretty heterogeneously but unpredictably around the
environment and a good day to forage in one direction is pretty much a good day to forage
in another. So, it’s a very finely-tuned recruitment system that doesn’t recruit them to any place
in particular but simply adjusts the outflow of foragers for the whole colony according
to the success of any particular forager anywhere. So, it’s the regulation of foraging by interaction
rate but it’s not by recruitment to any specific location. So, unlike some species of ants
that are probably more familiar to us that make pheromone trails to particular locations,
here they have an elaborate recruitment system in which there is no information about any
particular location. So, I want to end by just outlining the big questions that this
raises for me as a biologist. One is the question about stochasticity then the questions which
are the big questions for any biologist about development and evolution. The question about
stochasticity is when you consider–so this is the average response of 40 colonies to
removals for two minutes, and you can see that overall, there is this variability in
the rate of foraging and then after removals, it declines. But look at the arrow bars and
think about how, for an ant, it can’t be that the rate at which ants are coming in is very—-it’s
extremely variable for the ant that is using this rate, the input that it’s getting is
extremely variable. And then ants are ants, you know. No ant is making any complicated
calculations. They can’t do a lot of very precise averaging or anything and their response
is not fully deterministic. So, if you watch any ant, you will quickly learn that no ant
ever does exactly the right thing every time. So, what’s really interesting to me is that
with such stochastic input and such imprecise response on the part of the ants that the
system manages to work so well. The developmental question in biology is the question of how
this whole processes changes as the colony gets older and larger. And that developmental
question is really a scaling question. How is it that network size affects function?
What’s the relationship between the size of the colony and these dynamics? And the evolutionary
question is the one that arises when you realize that colonies actually vary in foraging behavior.
Some of them are much more sensitive to changes in the rate at which foragers come in than
others. And so one of the things that we’re doing now is using genetics to identify which
colonies have more offspring, tasked by their natural selection as acting on task allocation
and whether the colonies that are better foragers are actually collecting more food, having
more offspring colonies. Assuming that the variation among colonies is due to differences
among colonies in the particular algorithm that an ant is using, that is an ant that
says, “Okay, I need to meet ten foragers coming in per minute before I’m ready to go out to
forage,” in that colony, they’re going to do a lot less foraging than in another colony
where their threshold is lower and they say, “I only need two ants to come in per minute
before I’m ready to go out.” So, the differences among colonies in these thresholds would lead
to the overall differences that we see consistently year after year in how much a colony forages
and that that might have implications for their reproductive success and that would
be how natural selection was shaping task allocation. So, I want to end by trying to
make a connection with what all this has to do with Google by showing an e-mail I got
from somebody yesterday who was visiting my lab from Taiwan. And he’s—-he writes that,
“I visited Google with my friends twice when I lived at Palo Alto. This interesting company
have some particular ways to work. Their boss asks managers of every department not to limit
engineers how to solve problems and what have to do. Just give them a direction or a plan.
Engineers will make a temporary group and decide the ways to do. The process may be
longer, but opposingly may be more efficient than the way that managers decide if they
can. Each group seems to have no link between each other but the whole company works pretty
well.” So, I don’t know if that’s really true, but he goes on to say in praise of Google
that it works something like the ant colony he observed in my lab and it’s like this,
“This situation is like the colony of harvester ants I observed in the small room.” He means
the lab where I keep my ants. “I found that dead bodies and trash are gathered at some
nook far away from the nest. Some individuals bring them out and throw away when they just
walk for a short distance. But some individuals will pick up the trash when they suddenly
meet it and bring it more far away. Some trash are brought back and forth between the new-—between
two nooks.” Basically, the ants walk around carrying pieces of crud, they put it down,
they carry it back and forth. “It seems inefficient because they repeat steps in a longer process
from nest to the trash nook. However, when I saw the nest totally, it also seems to work
well. Each ant just knows something they have to do, but not an accurate process. I think
that maybe all the tasks in a nest are finished in this way and it makes the tasks more flexible,
not a straight line.” So, I don’t know if you guys walk around, kind of carrying bits
of garbage back and forth, and I don’t know if Google really works like this, but it’s
clear that there are lots of interesting processes in nature that do work something like this
and I’d be really interested to talk with people about analogies between the ways that
ants do things and maybe not so much how you do your work but how you perform the tasks
that you’re working on. So, thanks very much. Yes.
>>You talk about how maybe ants only have ten seconds worth of memory or so.
>>GORDON: Yes>>Presumably one reason is they’re really
small and they don’t have much brainpower. If ants could afford to be bigger and have
more mental resources but everything else stayed the same, do you think that they would
keep this model or would there be differences?>>GORDON: I think that this model–so, the
question is if ants were big enough to have bigger brains, would they keep this model
or would they do it differently? Well, I don’t know. But I think that–what’s amazing about
ants is that they have evolved ways of doing things really well that don’t require a big
brain. So, I think if you have a big brain, you think about what you’re doing very differently.
I mean, the key to the way that ants work is that no ant is thinking about what its
doing. No ant needs to understand what its doing or why and so what we see on the operation
of an ant colony is the ways to develop a system in which each component doesn’t have
any global information. Yes.>>So if the ants are blind and foraging during
the day [INDISTINCT] enough, why don’t they patrol and forage during the night?
>>GORDON: Question is if the ants are blind so they don’t need the light and its hard
work to forage during the day, why don’t they forage at night? Well, other ants are foraging
at night. They got there first. I don’t know. Yes.
>>I want to ask, do you really think it’s okay to study ants by destroying their homes
and painting them with toxic chemicals and stuff?
>>GORDON: Do I think its okay to study ants by destroying their homes and painting them
with toxic chemicals. Well, I don’t like destroying their homes so I don’t do it very much. Is
it okay? I don’t know. But the toxic chemicals don’t bother them very much because they do
fine with the paint. So, the ants that are working outside only have six weeks or so
to live anyway. And as far as we can tell, having painted thousands of ants, we’d never
caused an ant to die sooner by being painted.>>I’ve heard that painted queens will get
turned on–in beehives, painted queens will get thrown out, do you have any experience
with that?>>GORDON: He sort—-the question is whether
painted queens will get thrown out. Well, I have never actually painted a queen. The
queens that I have, say in the lab, are so precious that I wouldn’t let anybody near
them with anything. But the reason they’re getting thrown out is because they smell differently
and so with all the ants that we paint we have to let them dry out and then the ants
groom each other and they put the hydro carbons back over the paint. And so then they smell
okay and then they don’t get thrown out. Yes.>>So it’s kind of threshold function with
the decay when forager ants come out at the rate that patrol ants are returning.
>>GORDON: Yes.>>How come they return, they don’t come out
at a greater rate if the patrols are returning faster than expected?
>>GORDON: So, the question is why when we added beads at one second intervals, why–how
does that fit in with the threshold model and that’s a great question and it doesn’t
make sense in terms of the threshold model. So, the only situation in nature where the
ants would all come back that fast is if something that really bad happens. So, you could imagine
some extra rule on top of the threshold model that says if they all come back too fast,
this is a dangerous situation. But that’s really may just kind of invoking an extra
thing to explain the result that, as you say, doesn’t really make sense in terms of that
decay model. So, I don’t know is the short answer. Yes.
>>If the patrollers sense any danger, what does it mean? They don’t come back in the
nest in order for the foragers not to go out or what do they do? How do they communicate
the fact that there is a danger outside, don’t go outside?
>>GORDON: The question is how do the patrollers communicate that it’s dangerous outside? Well,
that’s the thing; they don’t communicate anything, but the rate at which they come back communicates
something. If they all got eaten or–so one of their predators, the main predator is a
horned lizard. If the patrollers all got eaten or if it was such a windy day as happens that
they all got blown away, then they wouldn’t come back. So the rate at which they come
back is the information. They don’t have—-bring any other information besides that.
>>So, if they sense the danger, they have to choose between going back into the nest
or not going back because going back to the nest would mean, “Okay, go ahead,” for the
foragers, right?>>GORDON: Yeah. The question is what do they
do if they sense a danger.>>But they would return?
>>GORDON: I don’t think that they-—I don’t think that they’re out there to sense danger.
It’s the fact of their going out and coming back that reflects this current situation.
But they don’t go out and say, “Wow, it looks like, you know, a pretty good day, but I’m
little worried about that lizardy thing over there.” They don’t do that. So it’s only the
rate at which they come back which gives the information. Yes.
>>All right. The–if the ants that go and look around and if they find something, they
come straight back, how do they know to go straight back? Or how do they know how to
go straight back?>>GORDON: The question is how do they find
their way back? It’s the same question for the patrollers and the foragers. We don’t
know. In some related species, they use the plane of polarized light from the sun, so
something about the direction of the sun. There are some ants that can see landmarks
but they’re in the minority, and these ants, we don’t think can see anything. So, we really
don’t know. One of the things that we’re thinking about now is whether the ants might use the
gradient of the hydrocarbons in the midden objects as a way to guide them into the nest
entrance from the edge of the mound. But that doesn’t explain how they get to the mound
in the first place. It’s clear that they partly use interactions with others and you can see
this in any ants that you look at that like the Argentine ants around here, that they–as
they pass each other, they touch the antennae. And if you—-if we mess with the foragers
so that the foragers coming back don’t have many foragers going out, they definitely take
a much more winding trajectory back. And so it seems that part of what guides them back
way far from the nest mound is the flow–is the interactions with others that they have
on they way back because as they get closer to the nest, there’s more ants. But we don’t
know all about how they do it. Yes.>>I have two questions. One, when the ants
are–when they’re coming back to tell the foragers that the patrols are returning, how
do you know that it has to do with the encounter and not just the concentration of the chemicals,
you know, in the ambient environment being built up as they return? That would explain
the decay function without requiring any sort of logic inside [INDISTINCT].
>>GORDON: The question is how do I know the difference between each ant’s experience of
encounters and the idea that that little pile of glass beads might create a sort of pool
of pheromone of a certain concentration. I don’t know that except that I see them touching
antennae and I don’t see the patrollers kind of clustering in a pile. But I don’t—-I
don’t that for sure. I had a film that I was going to show you but I feel like I was taking
too long, but you can see the–so maybe I’ll put this on while the–while the questions
are going. I think this will work. Oh, I have to approach it from the other end. I mean
it may be that an ant–oh, come on, don’t be silly. It may be that an ant somehow absorbs
its chemical environment over a certain time, but it would also have to be quite time dependent
or the rate wouldn’t matter, right? Because if they–I mean, I guess that’s another answer
is that if that they were accumulating just the net amount of cuticular hydrocarbon smell,
then the beads that we put in every three minutes should have had the same effect eventually
as the beads we put in one every ten seconds, and they didn’t. So, I guess that it could
be some kind of accumulation thing that it has to be very time dependent.
>>The other question was the inactive ants, where do they come in this [INDISTINCT].
>>GORDON: I think that they’re just a sync that some ants fall into there and never get
out, that those ants were once younger ants that were down with the brood and then they
end up in that pool and then they don’t–they never do anything after that. But it’s almost–in
a mature colony, it could be almost a third of the colony. So, one of the interesting
questions is whether that might be a kind of a buffer zone so that these dynamics that
depend on the rate of interaction, it might help to have a group of inert ants that dampen
oscillations or run away effects in the rate of interaction and keep the system more stable.
Yes.>>You mentioned that when patroller ants
go out and they find patroller ants from another colony, they don’t come back by the same route
that they went there. [INDISTINCT]>>GORDON: Yes.
>>Some way of signaling that you shouldn’t take this route for the foragers.
>>GORDON: Right.>>How do they find an alternate route back
to the [INDISTINCT]?>>GORDON: Well, what they look like they’re
doing is just meandering around. And so maybe they feel a little more meandering when they’ve
meet a patroller of another colony. And being a little more meandering tends–you know,
all of these are stochastic trends rather than, you know, strict deterministic rules.
So, this is film taken from inside the nest entrance with a fiber-optics microscope and
so you can see–that’s a nest maintenance worker coming up and wondering what the fiber-optics
microscope is, but eventually you see that they come past. And the idea is that the ants
then just inside the nest entrance here are using the rate at which they meet ants coming
back in from outside to decide whether to go out. And then soon you’ll see some ants
standing around outside and you can see that they’re very responsive to antennae contact
where they smell the hydrocarbons of another ant. So, the idea would be that a patroller
is out there wandering around and if nothing happens, it eventually wanders back. But if
it meets a patroller of another colony, it’s trajectory changes a little bit making it
less likely to come back the same way and making it less likely to put down the chemical
cue that, when enough of it accumulates, will get the foragers out there. So a group of,
maybe 50 patrollers can set the direction for thousands of foragers later on by some
simple rule that links-–that simply makes them a little more likely to avoid a place
where they meet the patrollers of the other colony. And we see the outcome of this in
that if ants of mature colonies meet their neighbors on a given day, they are likely
to avoid it the next. So, we know that they’re doing it somehow and that seems to be the
way that they’re doing it. Yes.>>Do patrollers fight?
>>GORDON: With other patrollers? No, we don’t see patrollers fight with other patrollers
and fighting is a strange thing that happens–on some days are fighting days. So, there are
days when they tend to, especially after a rain and we think maybe the rain washes away
hydrocarbon colony-specific signals on the ground. But there are some days after the
rains when the ants go pouring out all over the place and the foragers of neighboring
colonies meet and fight. And there are other days when we see just as much interaction,
but much less fighting. So, the probability of fighting per interaction changes very much
from day to day and it’s very much through the whole population and the only thing I
can think of is there’s some climatic conditions or something that affect the spread or the
volatility of some chemical that induces fighting. So, some days are fighting days, some days
are not and I don’t know why. Okay.>>Okay. That was great.
>>GORDON: Thanks.>>Really good.
>>GORDON: Thank you.

58 thoughts on “How Ant Colonies Get Things Done

  1. this reminds me a book i once read… i forgot the name of it, but it's connected with the idea of nano particles and AI

  2. One thing she mentioned is how she was a bit surprised that ants never do something with complete 'determinancy'. But this might well be an advantage instead of a downside (similar, although on a completely different scale, to how variance is built into reproduction/evolution).

    The big part of 'buffer' ants was really surprising to me, and what she mentioned at the very end about functioning against run-away effects sparked my interest.

  3. Wow.

    Your anti-intellectualism makes you kind of cool and badass. I bet if you kept hitting your skull against the hood of a Hummer you would win.

  4. This is nonsense, just looks like they patched together some pictures of ants sweeping etc.
    From what ive seen ants behaviour is necessary they have no contingent words like garbage or patroling. She is projecting onto them concepts that have nothing to do with ants.
    She provides no evidence that one ant is classified by other ants as a patroler or food collector.
    There is no forward planned task of an ant, it has to move & act depending on neccesity to act depending on its tiny situation.

  5. These small insect species have to be protected so they can build nests using materials in natural woodlands. Larger brained species are dependant on the smaller species for survival in the food chain. But we never really take notice of these delicate food chains, we just look at the indivual animals and not the relations between species so much.

  6. Scientists play an important role in analysing the natural world but sometimes declare theories that are later disproven by themselves or other scientists.
    So this video shows a scientist forming scientific theories based on observations, these theories can change later based on new observations.
    Sometimes human activities can influence scientific observations.
    So this scientist is providing a valid observation of insect phenomena in order to form theories based on peer review evaluation.

  7. For a short period each year, colonies produce both winged male and winged females.

    They then spread out to mate and found a new colony.

  8. HAHAHA!! She needs to work on her beginning. The "I study ants because…" just does not work. Makes me totally not interested.

  9. It seems like there ought to be a way to develop an automated recognition system that could very accurately track the flow of each individual ant into an out of the nest and what they were up to. It looks like it would save a lot of "horseflesh."

  10. I really dont like social bugs! why do almost all social bug races males die after having sex, example "bees" total suicide bugs! if they sting something big death by ripping of their back body, sex males die by ripping of their hmmm? dont really know if bee males got tiny dicks but they rip whatever they have of and die 🙁

  11. Very, very interesting video! Watched all of it 😀
    lol you can see she's not a great orator…But I think no one care. Her work and knowledge is very respectable 🙂

  12. there was an anuall mating i guess outside my house 2 years ago, a bunch of ants fell from the tree and were together. most had wings.

  13. Well I don't know much about ants, but I clicked on this to learn about ant colony optimization. This lecture was still interesting, especially near the end when talking about resource allocation as a function of network size.

  14. Interview with ant #43,574,065,002.564,213,943,772.002,546,548,132

    I don't know what you mean by happy! I just am now get the hell out of here before I squirt some pheromone and mark you for attack.

  15. The quran tells us about this 1400 years ago and how ants work, build, ect ect. Pretty interesting considering it was in a book over 1400 years old that has never changed. Fact. Check it out for yourself

  16. I put a teaspoon of sugar next to 3 ant colonies around my driveway (one pile next to each one). They are all the same kind of ants, those little black house ants. 1 of the colonies was actively eating it on the spot. The other 2 didn't show much interest and only a couple of ants were working at moving the grains into the hole and none of the ants were eating it on the spot. I repeated this the next day and got the same results. Why does one colony stuff their faces while the other 2 are so casual? My guess is the casual ones have a full pantry while the face stuffing ones have a empty one.

  17. Very interesting, thanks for sharing.  An ant can lift 20 times its own body weight. If a 175-pound man had the comparative strength of an ant, he could lift four tons.

  18. 0:45 already a false affirmation said as definite truth. "No one tells others what to do" is wrong in ant colony. The strongest ant tells the weaker. The one ant who is going to do the hard or dangerous job is the weakest ant, and they compare their strength by kick-boxing with antennas. Some species are less violent, but be sure that some ants are influencers anyway. If you don't acknowledge this, your whole consideration is pure waste of time. Mostly ants resembles us because they live in social large groups. so they do know love, compassion, but they know too laziness, frustration. They LEARN things because it's more efficient than instinct in social groups! If you follow a new ant she is clumsy in every aspect, then she learns any new skill with experience.

  19. 52:00 length of memory has nothing to do with brain's size. Take a crow with a grain a fraction of yours, he remembers faces better than you and longer. This approach of "10 second memory" is stupid, really stupid. 52:35 No ant need to know what's happening. OK but anyway, they DO. Believe me I've watched ants and they know what is happening. They don't know why there is a link between coming back and amount of food for sure, but they DO KNOW that there is more food when there is. They KNOW WHAT HAPPEN. Not knowing why doesn't mean you don't know that. When someone is in love with you you don't know why, but you can be sure that person is by the way the person look deeps into your eyes with emotion. Again this reasonning here from the biologists not only is stupid from the point of view of transferring what we know to ants, but it's stupid in the interpretation of what we human do itself and why. As as matter of fact we SOMETIMES know the reason of correlations. We tend to be very curious. But when we don't know why, we still know many correlations! Ants are the same. When you wanna know why ants do something, chances are it's the same reason we do because we resembles a lot. We tend to love whoever we need and is affectionate to us. They are the same. In a small colony, ants love their mother a lot. They love their puppaes a lot because soon they are going to wok for them 🙂 Lazy ants. Same as us. And if ever we happen to know scientifically why we love our babies, technically we refuse to accept it, we are feeling love is deep and not logic. Love is logic. I mean love toward specific things is logic. Direction of love is logic and solely logic. But love itself is NOT logic of course. It's the origin of life and intelligence and logic and anything. Ants do love too, they do fear and suffer, they do wonder, and while they don't know why, they sometimes wish they knew. Very much like us.

  20. Ants are NOT blind overall. Not even most ants are blind. But most see not further than an inch or much less. Some don't have eyes.

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