I study ants, and that's because I like to think about how organizations work. And in particular, how the simple parts of organizations interact to create the behavior of the whole organization. So, ant colonies are a good example of an organization like that, and there are many others. The web is one. There are many biological systems like that -- brains, cells, developing embryos.
組織がいかに作用するのかを見るのが好きなので アリの研究をしています いかにして 単純な部分同士の相互作用から 全体の習性が生じるのか見るのが好きです ですからアリコロニーはそのような組織の良い例なのです インターネットもその一例だと言えますし 脳 細胞 発達中の受精卵のような 生物学的システムもたくさんあります
There are about 10,000 species of ants. They all live in colonies consisting of one or a few queens, and then all the ants you see walking around are sterile female workers. And all ant colonies have in common that there's no central control. Nobody tells anybody what to do. The queen just lays the eggs. There's no management. No ant directs the behavior of any other ant. And I try to figure out how that works. And I've been working for the past 20 years on a population of seed-eating ants in southeastern Arizona.
アリは約一万種います どのアリも女王アリ1匹もしくは数匹がいるアリコロニーに住んでいて 外で見かけるアリはどれも産卵しない雌アリです どのアリコロニーにも共通するのは中央制御が存在せず 指揮監督がいません 女王アリが産卵するだけで 管理者はいません アリの行動を監督するアリはいなのです 私はその仕組みを解明しようとしています 過去20年間 アリゾナ州南東に生息する― 種を食べるアリの個体群を研究しています
Here's my study site. This is really a picture of ants, and the rabbit just happens to be there. And these ants are called harvester ants because they eat seeds. This is the nest of the mature colony, and there's the nest entrance. And they forage maybe for about 20 meters away, gather up the seeds and bring them back to the nest, and store them. And every year I go there and make a map of my study site. This is just a road. And it's not very big: it's about 250 meters on one side, 400 on the other. And every colony has a name, which is a number, which is painted on a rock. And I go there every year and look for all the colonies that were alive the year before, and figure out which ones have died, and put all the new ones on the map. And by doing this I know how old they all are. And because of that, I've been able to study how their behavior changes as the colony gets older and larger.
これが研究場所で アリの写真ですが たまたまウサギが写っています このアリが収穫アリと呼ばれるのは種を食べるからです これは成長したコロニーの巣と巣の入口です アリは20mほど先まで食糧を探しに行き 種を集めて巣に持ち帰り 貯えます 私は毎年ここに行き 研究場所の地図を作成しています これはただの道路で 広さは だいたい縦250m 横400mです どのコロニーにも識別番号をつけ 石に書いておきます 毎年 死んだコロニーを調べ 新しく出来た巣は地図に追加します こうすることでコロニーの年数を把握します その結果 コロニーの成長につれて 彼らの行動の変化を研究することが出来るのです
So I want to tell you about the life cycle of a colony. Ants never make more ants; colonies make more colonies. And they do that by each year sending out the reproductives -- those are the ones with wings -- on a mating flight. So every year, on the same day -- and it's a mystery exactly how that happens -- each colony sends out its virgin, unmated queens with wings, and the males, and they all fly to a common place. And they mate. And this shows a recently virgin queen. Here's her wings. And she's in the process of mating with this male, and there's another male on top waiting his turn. Often the queens mate more than once. And after that, the males all die. That's it for them.
コロニーのライフサイクルを説明します 着目すべきは個々のアリではなく 組織として働くコロニーです 毎年 羽のある繁殖アリを交尾飛行へと 送りだすことで繁殖させます いかに起きるかは謎ですが毎年同じ日に どのコロニーも羽のある処女女王アリと雄アリを送りだし みんな決まった場所へ飛んで行き 交尾をします これは最近の羽のついた処女女王アリです 女王アリは雄アリと交尾中で 別の雄アリが2匹の上で順番を待っています 女王アリはたいてい2回以上交尾をして 交尾後 雄アリは全て死にます ご苦労さま
(Laughter)
(笑)
And then the newly mated queens fly off somewhere, drop their wings, dig a hole and go into that hole and start laying eggs. And they will live for 15 or 20 years, continuing to lay eggs using the sperm from that original mating. So the queen goes down in there. She lays eggs, she feeds the larvae -- so an ant starts as an egg, then it's a larva. She feeds the larvae by regurgitating from her fat reserves. Then, as soon as the ants -- the first group of ants -- emerge, they're larvae. Then they're pupae. Then they come out as adult ants. They go out, they get the food, they dig the nest, and the queen never comes out again.
交尾をした女王アリは別の場所へと飛び 羽を落とし 穴を掘って中へ入り 産卵し始めます 女王アリは交尾の際に蓄えた精子を使って産卵し続け 約15~20年生きます 女王アリは地中に入り 卵を産んで それが幼虫になると 女王アリは蓄えてある― 脂肪を吐き出して幼虫を育てます そして第一番目のアリ集団が発生するや否や 幼虫 さなぎを経てアリの成虫になります アリは地上へ上がり 食べ物を得て 巣を掘り 女王は2度と地上に上がりません
So this is a one-year-old colony -- this happens to be 536. There's the nest entrance, there's a pencil for scale. So this is the colony founded by a queen the previous summer. This is a three-year-old colony. There's the nest entrance, there's a pencil for scale. They make a midden, a pile of refuse -- mostly the husks of the seeds that they eat. This is a five-year-old colony. This is the nest entrance, here's a pencil for scale. This is about as big as they get, about a meter across. And then this is how colony size and numbers of worker ants changes -- so this is about 10,000 worker ants -- changes as a function of colony age, in years. So it starts out with zero ants, just the founding queen, and it grows to a size of about 10 or 12 thousand ants when the colony is five. And it stays that size until the queen dies and there's nobody to make more ants, when she's about 15 or 20 years old. And it's when they reach this stable size, in numbers of ants, that they start to reproduce. That is, to send more winged queens and males to that year's mating flight. And I know how colony size changes as a function of colony age because I've dug up colonies of known age and counted all the ants. (Laughter) So that's not the most fun part of this research, although it's interesting.
これは出来てから1年経つコロニー536番です 巣の入口の大きさ比較に鉛筆を置いてあります これは昨夏出来たばかりのコロニーです これは3年目のコロニーです 巣の入口の大きさ比較に鉛筆を置いてあります アリが作るゴミの山は大方が食糧の種の皮です これは5年目のコロニーで 巣の入口の大きさ比較に鉛筆を置いてあります 巣は大きくても直径1m程度です このグラフはコロニーの大きさを表す働きアリの数が コロニーの年数とともにどう変化するかを示します これは働きアリ約1万匹です 最初は女王アリだけで 働きアリ0匹から始まり 5年経つまでに1万~1万2千匹ほどまで増加します その後 15~20歳になった女王アリが 死んでアリが生まれなくなるまで アリの数は変化しません アリの数がここまで安定すると アリは繁殖し始めます 羽のある女王アリと雄アリをその年の交尾飛行へと送りだすのです コロニーの使用年数と大きさの相関関係を把握しているのは 使用年数が確実なコロニーを掘り起こし すべてのアリを数えたからです 興味深いんですが この研究で一番楽しい部分とは言えません
(Laughter)
(笑)
Really the question that I think about with these ants is what I call task allocation. That's not just how is the colony organized, but how does it change what it's doing? How is it that the colony manages to adjust the numbers of workers performing each task as conditions change? So, things happen to an ant colony. When it rains in the summer, it floods in the desert. There's a lot of damage to the nest, and extra ants are needed to clean up that mess. When extra food becomes available -- and this is what everybody knows about picnics -- then extra ants are allocated to collect the food. So, with nobody telling anybody what to do, how is it that the colony manages to adjust the numbers of workers performing each task? And that's the process that I call task allocation.
私が知りたいのは このアリの仕事の割当てです コロニーの組織のされ方ではなく いかに動きが変わるのか? 状況の変化と共に 各仕事につく働きアリの数を いかにコロニーは調整しているのか? 色々なことが考えられます 夏の雨で砂漠が氾濫すれば 巣には大きな被害が出て 後片付けをするアリが余分に必要となります たくさん食糧が調達できる時は ピクニックでよく見かけるように 食糧収集にいつも以上のアリが配置されます 指揮監督なしで いかにコロニーでは 各仕事に就くアリの数を調整するのでしょう? これは私が仕事分配と呼んでいる過程です
And in harvester ants, I divide the tasks of the ants I see just outside the nest into these four categories: where an ant is foraging, when it's out along the foraging trail, searching for food or bringing food back. The patrollers -- that's supposed to be a magnifying glass -- are an interesting group that go out early in the morning before the foragers are active. They somehow choose the direction that the foragers will go, and by coming back -- just by making it back -- they tell the foragers that it's safe to go out. Then the nest maintenance workers work inside the nest, and I wanted to say that the nests look a lot like Bill Lishman's house. That is, that there are chambers inside, they line the walls of the chambers with moist soil and it dries to a kind of an adobe-like surface in it. It also looks very similar to some of the cave dwellings of the Hopi people that are in that area. And the nest maintenance workers do that inside the nest, and then they come out of the nest carrying bits of dry soil in their mandibles. So you see the nest maintenance workers come out with a bit of sand, put it down, turn around, and go back in. And finally, the midden workers put some kind of territorial chemical in the garbage. So what you see the midden workers doing is making a pile of refuse. On one day, it'll all be here, and then the next day they'll move it over there, and then they'll move it back. So that's what the midden workers do. And these four groups are just the ants outside the nest. So that's only about 25 percent of the colony, and they're the oldest ants.
巣の外で見かける アリの仕事を 4種に分類しました 外で食糧を調達してくる食糧アリ 虫メガネを持っている偵察アリは 食糧アリの活動前に 早朝から動きだす面白い集団です どういうわけか 偵察アリは食糧アリが行く方向を決め その方向から無事に帰ってくることで 外出しても安全だと食糧アリに教えます 整備アリは巣の中で働きます 巣はビル リシュマンの家にそっくりです と言うのも 中に小室があって 湿った土で小室の壁を覆うと 日干し煉瓦のように乾きます この地域に見られるホピ族の 洞窟住居にも類似しています 整備アリは巣の中をそのように施し 大あごで乾いた土を地上に運びます 砂を持って出てくる整備アリは 砂を置き 方向転換して 戻ります 最後に ごみアリは ある縄張り物質をゴミにつけます ごみアリはゴミの山を作るんです その日によって違った場所に ゴミの山を作りだします それがごみアリの仕事です この4つのグループは巣の外で仕事をするアリで 全体のわずか25%で 最年長アリです
So, an ant starts out somewhere near the queen. And when we dig up nests we find they're about as deep as the colony is wide, so about a meter deep for the big old nests. And then there's another long tunnel and a chamber, where we often find the queen, after eight hours of hacking away at the rock with pickaxes. I don't think that chamber has evolved because of me and my backhoe and my crew of students with pickaxes, but instead because when there's flooding, occasionally the colony has to go down deep. So there's this whole network of chambers. The queen's in there somewhere; she just lays eggs. There's the larvae, and they consume most of the food. And this is true of most ants -- that the ants you see walking around don't do much eating. They bring it back and feed it to the larvae. When the foragers come in with food, they just drop it into the upper chamber, and other ants come up from below, get the food, bring it back, husk the seeds, and pile them up. There are nest maintenance workers working throughout the nest. And curiously, and interestingly, it looks as though at any time about half the ants in the colony are just doing nothing. So, despite what it says in the Bible, about, you know, "Look to the ant, thou sluggard," in fact, you could think of those ants as reserves. That is to say, if something happened -- and I've never seen anything like this happen, but I've only been looking for 20 years -- if something happened, they might all come out if they were needed. But in fact, mostly they're just hanging around in there.
どのアリも女王アリの近くから出てきたわけです 掘り起こすと 巣はコロニーの幅ほどの深さがあり 大きくて古い巣は深さが1mほどあります つるはしで岩を8時間叩き割って行くと 長い通路の奥の小部屋に女王アリを見つけます 我々がショベルカーやつるはしで掘り起こした為に 小室がこの形になったとは思いません 時々起こる洪水のため コロニーは深さがなくてはいけません それで これほどまでの小室があるのです 女王アリはどこかで産卵だけしています 幼虫は食糧のほとんどを消費します ほとんどのアリに共通していることですが 外で見かけるアリはあまり食べることをしません 食糧を調達し幼虫に餌付けします 食糧アリが食糧を持ってくると上部の小室へと投げ込みます 下から別のアリがやってきて食糧を受け取り 運んで種の皮をむき 積み上げます 整備アリは巣の至る所で働いています 面白いことに どんな時も コロニーにいるアリの約半分は 何もしていないかのように見えるのです 聖書には “怠け者よ アリのところに行ってみよ” とありますが このようなアリは補欠選手と考えてもいいでしょう 私の20年の研究では見たことがありませんが いざという時には 全てのアリが出てくるかも知れません でも 大抵その辺でうろついているだけです
And I think it's a very interesting question -- what is there about the way the colony is organized that might give some function to a reserve of ants who are doing nothing? And they sort of stand as a buffer in between the ants working deep inside the nest and the ants working outside. And if you mark ants that are working outside, and dig up a colony, you never see them deep down. So what's happening is that the ants work inside the nest when they're younger. They somehow get into this reserve. And then eventually they get recruited to join this exterior workforce. And once they belong to the ants that work outside, they never go back down. Now ants -- most ants, including these, don't see very well. They have eyes, they can distinguish between light and dark, but they mostly work by smell. So just to reinforce that what you might have thought about ant queens isn't true -- you know, even if the queen did have the intelligence to send chemical messages through this whole network of chambers to tell the ants outside what to do, there is no way that such messages could make it in time to see the shifts in the allocation of workers that we actually see outside the nest. So that's one way that we know the queen isn't directing the behavior of the colony.
私が興味を惹かれるのは 何もしていないアリの予備軍に何か役割を出しうる コロニーの組織のされ方とは何なのか? 何もしないアリは巣の奥深くで働くアリと 外で働くアリの調停者のような立場にいます 外で働くアリに印をつけてコロニーを掘ると 絶対に彼らを巣の奥で見かけません と言うのもアリは若い時に巣の中で働くのです いつの間にか この補欠組に入り ついには外で働くアリとなります 一度外で働くようになると地中には戻りません 大方のアリは目がよく見えません 明暗を見分けられる程度の目で ほとんどを嗅覚に頼っています ですから女王アリが指揮していると思われたら それは違います 女王アリがアリ全体に指令を出せる― 化学的なメッセージを送る知能を持っていたとしても そんなメッセージで 適切なタイミングに働きアリの仕事割り当ての 変更を届けられることは絶対にあり得ないので 女王はコロニーの動きを指揮していないと分かるのです
So when I first set out to work on task allocation, my first question was, "What's the relationship between the ants doing different tasks? Does it matter to the foragers what the nest maintenance workers are doing? Does it matter to the midden workers what the patrollers are doing?" And I was working in the context of a view of ant colonies in which each ant was somehow dedicated to its task from birth and sort of performed independently of the others, knowing its place on the assembly line. And instead I wanted to ask, "How are the different task groups interdependent?"
仕事分配の研究を始めたとき 最初の疑問は “別の仕事をするアリ同士の 関係はどうなっているか” でした 食糧アリにとって整備アリが何をしているのか問題なのか? ごみアリにとって偵察アリが何をしているのか問題なのか? 生まれてからずっと自分の仕事に徹し 流れ作業における 自分の位置は知っていても 他のアリとは独立して作業しているという見方で 研究をしていました その代わりに異なるグループ間の依存関係を問う事にしました
So I did experiments where I changed one thing. So for example, I created more work for the nest maintenance workers by putting out a pile of toothpicks near the nest entrance, early in the morning when the nest maintenance workers are first active. This is what it looks like about 20 minutes later. Here it is about 40 minutes later. And the nest maintenance workers just take all the toothpicks to the outer edge of the nest mound and leave them there. And what I wanted to know was, "OK, here's a situation where extra nest maintenance workers were recruited -- is this going to have any effect on the workers performing other tasks?" Then we repeated all those experiments with the ants marked. So here's some blue nest maintenance workers. And lately we've gotten more sophisticated and we have this three-color system. And we can mark them individually so we know which ant is which. We started out with model airplane paint and then we found these wonderful little Japanese markers, and they work really well. And so just to summarize the result, well it turns out that yes, the different tasks are interdependent. So, if I change the numbers performing one task, it changes the numbers performing another. So for example, if I make a mess that the nest maintenance workers have to clean up, then I see fewer ants out foraging. And this was true for all the pair-wise combinations of tasks.
条件を一つ変えて実験をしてみました 例えば 整備アリが活動をし始める朝早くに 巣の入口近くに楊枝を積み上げて 整備アリの仕事を増やしてみました 約20分後にはこのようになり 約40分後にはこのようになりました 整備アリは楊枝を巣の端に運び そこに放置するのです それで次に浮かんだ疑問は いつも以上の整備アリが召集された場合 別の仕事をしているアリに影響は出るのか? 印をつけたアリで再度実験を行いました 青く印をつけた整備アリです 最近は以前より凝って 3色使っています 1匹ずつ印をつけるので個体が識別できます 最初はプラモデル用のペンを 使いましたが その後 日本製の 優れたペンを見つけました 結果はと言うと 異なる仕事は互いに関係があり ある仕事をしているアリの数を変えれば 別の仕事をするアリの数も変わります 例えば 私が何か散らかして 整備アリの仕事量を増やせば 食糧アリは見かけなくなりました これはすべての仕事に共通していました
And the second result, which was surprising to a lot of people, was that ants actually switch tasks. The same ant doesn't do the same task over and over its whole life. So for example, if I put out extra food, everybody else -- the midden workers stop doing midden work and go get the food, they become foragers. The nest maintenance workers become foragers. The patrollers become foragers. But not every transition is possible. And this shows how it works. Like I just said, if there is more food to collect, the patrollers, the midden workers, the nest maintenance workers will all change to forage. If there's more patrolling to do -- so I created a disturbance, so extra patrollers were needed -- the nest maintenance workers will switch to patrol. But if more nest maintenance work is needed -- for example, if I put out a bunch of toothpicks -- then nobody will ever switch back to nest maintenance, they have to get nest maintenance workers from inside the nest. So foraging acts as a sink, and the ants inside the nest act as a source. And finally, it looks like each ant is deciding moment to moment whether to be active or not.
多くの人を驚かせた2つ目の結果は アリが役割を切り替えることです アリは一生を通じて同じ仕事はしません 例えば 余分な食糧を置いてみると ごみアリはごみ収集を止め食糧調達に行き 食糧アリと化します 整備アリが食糧アリとなり 偵察アリが食糧アリになります 全ての役割変換が可能なわけではありません 先ほどのように 食糧があれば 偵察アリもごみアリも 整備アリも食糧アリに替わります 障害を作ることで 通常よりも偵察が必要ならば 整備アリは偵察アリに替わります しかし 楊枝を積み上げて 整備の仕事を増やしても 整備アリに戻るアリはおらず 巣の中から整備アリを召集しなくてはいけません 巣の中のアリからスタートして 食糧探しがゴールです 最後に アリが活動するかどうかは その時々で決めているようです
So, for example, when there's extra nest maintenance work to do, it's not that the foragers switch over. I know that they don't do that. But the foragers somehow decide not to come out. And here was the most intriguing result: the task allocation. This process changes with colony age, and it changes like this. When I do these experiments with older colonies -- so ones that are five years or older -- they're much more consistent from one time to another and much more homeostatic. The worse things get, the more I hassle them, the more they act like undisturbed colonies. Whereas the young, small colonies -- the two-year-old colonies of just 2,000 ants -- are much more variable. And the amazing thing about this is that an ant lives only a year. It could be this year, or this year. So, the ants in the older colony that seem to be more stable are not any older than the ants in the younger colony. It's not due to the experience of older, wiser ants. Instead, something about the organization must be changing as the colony gets older. And the obvious thing that's changing is its size.
例えば 整備の仕事が増えても 食糧アリは仕事を切り替えずに 巣から出てきません 一番興味深い結果だったのは仕事分担です この過程はコロニーの古さと共に変化します 5年から10年経過した― 古めのコロニーで実験をすると 一貫性がより強く見られ恒常的です 状況が悪化するほど せかされるほど 平静を装います それに対し 新しくて小さな 二千匹いる2年目のコロニーはもっと変わりやすいのです 驚くのはアリの寿命がわずか1年であること いつ生まれても1年です 古めのコロニーの落ち着いて見えるアリは 新しいコロニーにいるアリより年上という訳ではないのです 年の功ではありません その代わりに組織に関わる何かが コロニーが古くなるにつれて変わるに違いありません 明らかに変化しているのはコロニーの大きさです
So since I've had this result, I've spent a lot of time trying to figure out what kinds of decision rules -- very simple, local, probably olfactory, chemical rules could an ant could be using, since no ant can assess the global situation -- that would have the outcome that I see, these predictable dynamics, in who does what task. And it would change as the colony gets larger. And what I've found out is that ants are using a network of antennal contact. So anybody who's ever looked at ants has seen them touch antennae. They smell with their antennae. When one ant touches another, it's smelling it, and it can tell, for example, whether the other ant is a nest mate because ants cover themselves and each other, through grooming, with a layer of grease, which carries a colony-specific odor. And what we're learning is that an ant uses the pattern of its antennal contacts, the rate at which it meets ants of other tasks, in deciding what to do. And so what the message is, is not any message that they transmit from one ant to another, but the pattern. The pattern itself is the message. And I'll tell you a little bit more about that.
この結果を得てから 全体を見れるアリがいないことを踏まえて 単純で 局所的で おそらく嗅覚に関わり 化学的で 観察可能なアリの決断規則を 突きとめようと時間をかけてきました 誰がどの仕事をするのか予測できる過程 そしてそれはコロニーの老化と共に変化します 私が発見したのは アリは触角を使った連絡網を使っていることです アリを観察したことのある方なら知っているでしょう アリは触角で匂いをかぎ分けます アリがアリを触るのは 匂いを嗅いでいるのです 同じ巣の仲間かどうか確認できるのです コロニー独自の匂いがする油の層で お互いにグルーミングして体を覆います 今わかって来ているのはアリは触角接触のパターンを使い 他の仕事担当のアリと会う割合で何をするのか決めています アリからアリへのメッセージではなく パターンがあるのです パターン自体がメッセージです 後からまた説明しますが
But first you might be wondering: how is it that an ant can tell, for example, I'm a forager. I expect to meet another forager every so often. But if instead I start to meet a higher number of nest maintenance workers, I'm less likely to forage. So it has to know the difference between a forager and a nest maintenance worker. And we've learned that, in this species -- and I suspect in others as well -- these hydrocarbons, this layer of grease on the outside of ants, is different as ants perform different tasks. And we've done experiments that show that that's because the longer an ant stays outside, the more these simple hydrocarbons on its surface change, and so they come to smell different by doing different tasks. And they can use that task-specific odor in cuticular hydrocarbons -- they can use that in their brief antennal contacts to somehow keep track of the rate at which they're meeting ants of certain tasks. And we've just recently demonstrated this by putting extract of hydrocarbons on little glass beads, and dropping the beads gently down into the nest entrance at the right rate. And it turns out that ants will respond to the right rate of contact with a glass bead with hydrocarbon extract on it, as they would to contact with real ants.
アリはいかに自分の役割が わかるのでしょう 例えば自分が食糧アリならば 他の食糧アリと頻繁に会うはずです その代わりに沢山の整備アリと会ったら おそらく食糧探しには行きません そうなると食糧アリと整備アリの違いを 見分けなくてはいけないのです 他の種も同じだと思いますが この種のアリの体についている― 油の層の炭化水素は 仕事により異なることがわかりました 実験でわかったのは アリが外にいる時間が長くなるほど 体の表面の単純な炭化水素が変わるので 仕事によって体の匂いも異なるのです 仕事ごとに違う匂いを角皮の炭化水素に使えるのです 短時間の触角の接触の中で 匂いを使って 特定の仕事のアリと会う割合を把握します 我々は最近 炭化水素の抽出物を 小さなガラス玉につけ 適切な割合で 巣の入口にそっと落とすことで証明してみました そうするとアリは炭化水素つきのガラス玉に 本物のアリと接触するように 反応することがわかったのです
So I want now to show you a bit of film -- and this will start out, first of all, showing you the nest entrance. So the idea is that ants are coming in and out of the nest entrance. They've gone out to do different tasks, and the rate at which they meet as they come in and out of the nest entrance determines, or influences, each ant's decision about whether to go out, and which task to perform. This is taken through a fiber optics microscope. It's down inside the nest. In the beginning you see the ants just kind of engaging with the fiber optics microscope. But the idea is that the ants are in there, and each ant is experiencing a certain flow of ants past it -- a stream of contacts with other ants. And the pattern of these interactions determines whether the ant comes back out, and what it does when it comes back out. You can also see this in the ants just outside the nest entrance like these. Each ant, then, as it comes back in, is contacting other ants. And the ants that are waiting just inside the nest entrance to decide whether to go out on their next trip, are contacting the ants coming in.
少し映像をお見せしますが まず見えるのは巣の入口部分です アリが巣に出たり入ったりしています 別の仕事をしに出て行きました アリが出入りするときに 別のアリと会う割合が 外に出るかどうかや どの仕事をするかという判断に影響を与えます 光ファイバー顕微鏡を使って巣の中を撮影しました 初めに光ファイバー顕微鏡と 接触しているのアリが見えます 巣の中のアリはどれも すれ違って行くアリを感知し 他のアリと接触しています この関わり合いのパターンで アリが外に戻るかどうか そして外でどの仕事をするのかを決めます このような巣のすぐ外にいるアリにも見られることです どのアリも巣の中に戻ると他のアリと接触しています 巣の入り口のすぐ中で待っていたアリは 入ってくるアリと接触して 外に出かけるか決めます
So, what's interesting about this system is that it's messy. It's variable. It's noisy. And, in particular, in two ways. The first is that the experience of the ant -- of each ant -- can't be very predictable. Because the rate at which ants come back depends on all the little things that happen to an ant as it goes out and does its task outside. And the second thing is that an ant's ability to assess this pattern must be very crude because no ant can do any sophisticated counting. So, we do a lot of simulation and modeling, and also experimental work, to try to figure out how those two kinds of noise combine to, in the aggregate, produce the predictable behavior of ant colonies.
このシステムの面白い部分は乱雑なところです 特に2つの点において可変的で混沌としています 一つ目にそれぞれのアリの経験はあまり予測できません なぜなら アリは外に出て仕事をする為 アリが戻ってくる割合は アリに起きている状況次第だからです 二つ目は高度な計算が出来るアリはいないので このパターンを評価するアリの能力はいい加減に違いないのです ですから シミュレーションやモデリングや実験をたくさん行い その2種類の情報がコロニーの 予測出来る行動を生み出すのか探究しています
Again, I don't want to say that this kind of haphazard pattern of interactions produces a factory that works with the precision and efficiency of clockwork. In fact, if you watch ants at all, you end up trying to help them because they never seem to be doing anything exactly the way that you think that they ought to be doing it. So it's not really that out of these haphazard contacts, perfection arises. But it works pretty well. Ants have been around for several hundred million years. They cover the earth, except for Antarctica. Something that they're doing is clearly successful enough that this pattern of haphazard contacts, in the aggregate, produces something that allows ants to make a lot more ants. And one of the things that we're studying is how natural selection might be acting now to shape this use of interaction patterns -- this network of interaction patterns -- to perhaps increase the foraging efficiency of ant colonies.
このような偶然の接触パターンが 正確で効率的な時計仕掛けの工場を作るというのではありません 実際アリの観察を始めると 彼らがすべきことを 彼らがしているようには見えないため 結局手助けしてしまうことになります ですから偶然の接触から完璧な状態が生まれるのではありません でも うまく働いています アリは数百万年も生きてきた生き物で 南極大陸を除き 至る所で生息しています 彼らの偶然的な接触のパターンは 全体としてアリを繁栄させるのを可能にする― 何かを可能にしているのです 我々は自然選択がいかにして この相互作用パターンの使用やネットワークを形作るのかに影響し コロニーの食糧探しの効率化を上げるのに 影響しているかを研究しています
So the one thing, though, that I want you to remember about this is that these patterns of interactions are something that you'd expect to be closely connected to colony size. The simplest idea is that when an ant is in a small colony -- and an ant in a large colony can use the same rule, like "I expect to meet another forager every three seconds." But in a small colony, it's likely to meet fewer foragers, just because there are fewer other foragers there to meet. So this is the kind of rule that, as the colony develops and gets older and larger, will produce different behavior in an old colony and a small young one.
覚えておいていただきたいのは この相互作用パターンは コロニーの大きさと密接に関係していると考えられるということです 一番単純な考えは アリがコロニーの大きさに関係なく 同じルールを使うという考えです 例えば “3秒毎に食糧アリと会う” と予測しても 小さいコロニーで それほど食糧アリに会いません 食糧アリの数が少ないからなのです この種のルールがあれば コロニーが成長するにつれて 異なる行動が生み出されます
Thank you.
ありがとうございました
(Applause)
(拍手)