# Why does evolution "look" so directed? **URL:** \ **Category:** Factual Questions\ **Created:** [October 15, 2013, 3:22am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280 "2013-10-15T03:22:07Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [October 15, 2013, 3:30pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/21 "2013-10-15T15:30:25Z")
> [@Chronos](#): > > There’s also a tendency with evolution for creatures to settle on some schtick and develop it further. A large part of the great apes’ schtick is that they’re more intelligent than most other animals, so it’s not too surprising that one particular lineage of apes took that schtick to an extreme. This isn’t really any different from some theropods specializing in biting things with a really big mouth, leading eventually to T. rex. From our point of view, evolution looks “directed” towards intelligence, and a smarter creature seems “more evolved” than a stupid one… But from a rex’s point of view, evolution is directed towards big jaws and teeth, and a more mawsome creature is “more evolved” than a small-mouthed one. The thing about evolution - an animal that takes advantage of an opportunity to live, eat, and breed with survive more often. Extra bits “cost” a lot in terms of food and survival. The cheetah or wolf, for example, does not need a huge brain. Once you are fast, you only need enough brainpower to figure out where the prey will zig or zag next, and how to avoid the horns when they corner it. Extra brain power takes a lot of extra food to keep working - it it’s not going to get you fed or laid more often, you will lose during bad times to the small-brained wolf or cheetah who will live on less food. It’s always a trade-off. This is also why humans have limited muscle power. Muscles takes food to maintain, even at rest. To strong a human, or too big, will be the most vulnerable during famine. Basically, the result in evolution is the most appropriate compromise - the “Goldilocks” zone, just perfect. If an organism is fairly specialized or exotic, it means they have latched onto a very reliable source of food (at least at one time). Then, like giraffes and the tall trees, they have become more and more specialized over time to better exploit that ecological “niche”. ---
**Author:** ![Don\_t\_Panic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/don_t_panic/32/398_2.png) [@Don\_t\_Panic](https://boards.straightdope.com/u/Don_t_Panic)\ **Post date:** [October 15, 2013, 3:33pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/22 "2013-10-15T15:33:40Z")
> [@Trinopus](#): > > It isn’t enough to look at the really elegant parts of nature – eagle’s wings and wolves’ teeth. It’s when you look at the whole picture, you see the messy, sloppy, undirected and extremely unintelligent bits. These point the way to the truth. For a nice example of this, I like [this video](http://www.youtube.com/watch?v=cO1a1Ek-HD0), where Richard Dawkins talks about the laryngeal nerve. This is a nerve that goes from the brain to the larynx. In some of our early ancestors, it took a pretty direct route, but because of historical accidents, it now takes weird detours around the bodies of large animals (and humans). In a giraffe, it only really needs to go two inches, but instead of hopping right across, it goes all the way down the giraffe’s neck and back up again. It’s just the kind of thing that evolution does that a designer would never do. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [October 15, 2013, 4:34pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/23 "2013-10-15T16:34:03Z")
> [@Aji\_de\_Gallina](#): > > I know evolution is random No. It’s not. Failing to understand this is behind 90% of the misconceptions I see about evolution. Evolution is NOT random. The biosphere of the earth is NOT the result of eleventy gazillion coin flips all landing heads-up. Mutations are random; selection is NOT. That’s absolutely critical to understanding how it is that we see what we see. Selection selects. Nonrandomly. That’s why it’s called that. It’s a natural, undirected, purely automatic system that is the result of competition between genetic variants in the environment. That is the driving force. That is what brought us from the primordial soup to chicken noodle soup. And chickens. And the wheat that made the noodles, and the virus that gave you the cold that you’re eating the soup to soothe. There is no goal, there is no direction, but there is, vitally, nonrandom selection. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [October 15, 2013, 4:49pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/24 "2013-10-15T16:49:44Z")
> [@Martian Bigfoot](#): > > For a nice example of this, …laryngeal nerve. [Why Evolution is True](http://www.barnesandnoble.com/w/why-evolution-is-true-coyne/1116745079?ean=9780143116646) contains many more neat examples like this of things that would make no sense if they were “designed”. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 15, 2013, 4:55pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/25 "2013-10-15T16:55:48Z")
> [@Glazer](#): > > Does a Platypus look directed? It would if you were a Platypus. An intelligent Platypus would be sure he was the pinnacle of evolution and the crown of creation. A hairless, bipedal, terrestrial ape with a hypertrophied brain would seem just as outlandish and unlikely as a Platypus if we weren’t one ourselves. > [@Sailboat](#): > > Well, there’s some evidence now that H. sapiens may have interbred with at least Neanderthals and Denisovians instead of just murdering them. Most likely it was both, as has been the case whenever a group of _H. sapiens_ met a less advanced group of our own species. But the group ends up extinct except for a few genes still carried in the victorious population. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [October 15, 2013, 5:02pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/26 "2013-10-15T17:02:18Z")
The element of direction only seems to hold true when the environment has consistent selective pressures. As long as being big is selected for, you expect generation 100 to bigger and generation 10,000 to be bigger still. But at some point, big will no longer be selected for - maybe your bones aren’t strong enough, or you can’t find enough food, etc. Then (again, assuming no change in the selective pressures) a species is likely to settle into an equilibrium in regards to size. Some species have reached remarkably stable positions. Crocodilians, for example. On the other hand, you look at something like Darwin’s finches and you see that beak size skews all over the place. You can look at any individual species and see the selective pressures that lead to that particular beak, but if you look at all of the species or look at them over a long-enough time frame, there’s no overall pattern. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 15, 2013, 5:59pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/27 "2013-10-15T17:59:35Z")
> [@dracoi](#): > > The element of direction only seems to hold true when the environment has consistent selective pressures. As long as being big is selected for, you expect generation 100 to bigger and generation 10,000 to be bigger still. But at some point, big will no longer be selected for - maybe your bones aren’t strong enough, or you can’t find enough food, etc. Then (again, assuming no change in the selective pressures) a species is likely to settle into an equilibrium in regards to size. Although increasing size is a trend in hominid evolution, with _Homo erectus_ being much larger that _Australopithecus_, that was of course reversed in the so-called “hobbits” of Flores, _Homo floresensis_. Likewise some modern human populations are similar in size to _Australopithecus_. ---
**Author:** ![Glazer](https://avatars.discourse-cdn.com/v4/letter/g/a88e57/32.png) [@Glazer](https://boards.straightdope.com/u/Glazer)\ **Post date:** [October 15, 2013, 6:05pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/28 "2013-10-15T18:05:03Z")
> [@Colibri](#): > > It would if you were a Platypus. An intelligent Platypus would be sure he was the pinnacle of evolution and the crown of creation. > > A hairless, bipedal, terrestrial ape with a hypertrophied brain would seem just as outlandish and unlikely as a Platypus if we weren’t one ourselves. Tough room. ---
**Author:** ![jharvey963](https://avatars.discourse-cdn.com/v4/letter/j/54ee81/32.png) [@jharvey963](https://boards.straightdope.com/u/jharvey963)\ **Post date:** [October 15, 2013, 8:20pm UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/29 "2013-10-15T20:20:21Z")
> [@Sailboat](#): > > Well, there’s some evidence now that H. sapiens may have interbred with at least Neanderthals and Denisovians instead of just murdering them. > > Still, either way they were fucked. 😃 I see what you did there. 😃 J. ---
**Author:** ![Dorjan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dorjan/32/12440_2.png) [@Dorjan](https://boards.straightdope.com/u/Dorjan)\ **Post date:** [October 16, 2013, 3:22am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/30 "2013-10-16T03:22:37Z")
For the most part, you’re only seeing the successes. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [October 16, 2013, 3:49am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/31 "2013-10-16T03:49:12Z")
> [@Smeghead](#): > > No. It’s not. Failing to understand this is behind 90% of the misconceptions I see about evolution. Evolution is NOT random. The biosphere of the earth is NOT the result of eleventy gazillion coin flips all landing heads-up. > > Mutations are random; selection is NOT. That’s absolutely critical to understanding how it is that we see what we see. Selection selects. Nonrandomly. That’s why it’s called that. It’s a natural, undirected, purely automatic system that is the result of competition between genetic variants in the environment. That is the driving force. That is what brought us from the primordial soup to chicken noodle soup. And chickens. And the wheat that made the noodles, and the virus that gave you the cold that you’re eating the soup to soothe. There is no goal, there is no direction, but there is, vitally, nonrandom selection. If you’d quoted my completely you’d have put > [@](#): > > I know evolution is random and the whole Darwin-natural-selection thingy There is a gigantic random element. Natural selection only acts after the random event. You can only play the cards you were dealt. “Evolution is random” is a correct enough one-sentence summary of evolution. > [@Dorjan](#): > > For the most part, you’re only seeing the successes. That is, I think, a large part of the “looks like directed” part. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 16, 2013, 3:53am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/32 "2013-10-16T03:53:45Z")
> [@Aji\_de\_Gallina](#): > > “Evolution is random” is a correct enough one-sentence summary of evolution. No it isn’t. It is extremely misleading. The reasons have already been explained. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 16, 2013, 4:01am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/33 "2013-10-16T04:01:23Z")
> [@Aji\_de\_Gallina](#): > > There is a gigantic random element. Natural selection only acts after the random event. You can only play the cards you were dealt. > “Evolution is random” is a correct enough one-sentence summary of evolution. Yes, there is an ineliminable random element in evolution, but “Evolution is random,” is very far from being a correct, or even “correct enough” (whatever that means), summary of the theory. It is not just false, it is actively misleading. The belief that it _is_ an adequate summary is indeed what lies behind much of the misunderstanding of evolutionary theory that is out there, and at least a part of the appeal of creationism. ---
**Author:** ![Hentor\_the\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@Hentor\_the\_Barbarian](https://boards.straightdope.com/u/Hentor_the_Barbarian)\ **Post date:** [October 16, 2013, 4:03am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/34 "2013-10-16T04:03:14Z")
> [@Aji\_de\_Gallina](#): > > “Evolution is random” is a correct enough one-sentence summary of evolution. No it is not. Not even close. Consider the mechanism of natural selection. This is a systematically selective process, not a random one. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 16, 2013, 4:11am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/35 "2013-10-16T04:11:57Z")
> [@Colibri](#): > > Although increasing size is a trend in hominid evolution, with _Homo erectus_ being much larger that _Australopithecus_, that was of course reversed in the so-called “hobbits” of Flores, _Homo floresensis_. Likewise some modern human populations are similar in size to _Australopithecus_. \*Homo floresiensis. \* 😉 But you don’t even have to reference that species, since the type specimen for \*H. ergaster \* (the so-called Turkana Boy) would have been larger than your average _H. sapiens_ today. Still, _H. erectus_ was a wide ranging species and local populations probably had a range of sizes depending on the environment they found themselves in. Which is not unlike our own species. And of course the Australopithecines (a genus, not a species) ranged widely in size themselves, although the versions that seem to have evolved in us\* were on the smallish side. \*There is still debate about which exact species of that genus were our ancestors. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [October 16, 2013, 4:51am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/36 "2013-10-16T04:51:50Z")
> [@Colibri](#): > > No it isn’t. It is extremely misleading. The reasons have already been explained. > [@njtt](#): > > Yes, there is an ineliminable random element in evolution, but “Evolution is random,” is very far from being a correct, or even “correct enough” (whatever that means), summary of the theory. It is not just false, it is actively misleading. The belief that it _is_ an adequate summary is indeed what lies behind much of the misunderstanding of evolutionary theory that is out there, and at least a part of the appeal of creationism. > [@Hentor\_the\_Barbarian](#): > > No it is not. Not even close. Consider the mechanism of natural selection. This is a systematically selective process, not a random one. Mutations are random and natural selection is non-directed (in the sense that it’s a dumb natural event, no one’s guiding it) and usually very slow (vis a vis a species’ generation time) so that it is unpredictable, that “random” is the right word. We could go really anal and say the real randomness is non-existant in the non-quantic world and that coin-fliiping and dice-throwing and lottery-number-ball-selection are not REALLY random, because we could analize the initial conjditions and come up with the result. I something is not intentionally directed and the results cannot even remotely be predicted then it’s real-world random if not scientifically random. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [October 16, 2013, 6:36am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/37 "2013-10-16T06:36:26Z")
You say “you can only play the cards you were dealt.” but in fact evolution gets dealt millions of hands. True it is not directed, but neither is it random, since only mutations that lead to reproductive success spread. There are tons of heuristics for search space exploration, such as simulated annealing and of course genetic algorithms, and while you can’t predetermine which local optimum they wind up at, they are definitely not random, and in fact can be compared with truly random heuristics. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [October 16, 2013, 6:51am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/38 "2013-10-16T06:51:25Z")
> [@dracoi](#): > > The element of direction only seems to hold true when the environment has consistent selective pressures. As long as being big is selected for, you expect generation 100 to bigger and generation 10,000 to be bigger still. But at some point, big will no longer be selected for - maybe your bones aren’t strong enough, or you can’t find enough food, etc. Then (again, assuming no change in the selective pressures) a species is likely to settle into an equilibrium in regards to size. > > Some species have reached remarkably stable positions. Crocodilians, for example. > > On the other hand, you look at something like Darwin’s finches and you see that beak size skews all over the place. You can look at any individual species and see the selective pressures that lead to that particular beak, but if you look at all of the species or look at them over a long-enough time frame, there’s no overall pattern. Then there’s self-selection - the finches with big strong seed-cracking beaks, or thin pointy insect-eating beaks, who mated with anything but the same would produce a beak likely only half as good at either task and likely to lose in the competition for food (unless each type of food frequently disappeared and the ability to switch was an advantage). By this method one species gradually becomes two specialized species with different characteristics. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 16, 2013, 7:23am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/39 "2013-10-16T07:23:49Z")
> [@Aji\_de\_Gallina](#): > > Mutations are random and natural selection is non-directed (in the sense that it’s a dumb natural event, no one’s guiding it) and usually very slow (vis a vis a species’ generation time) so that it is unpredictable, that “random” is the right word. > > We could go really anal and say the real randomness is non-existant in the non-quantic world and that coin-fliiping and dice-throwing and lottery-number-ball-selection are not REALLY random, because we could analize the initial conjditions and come up with the result. > > I something is not intentionally directed and the results cannot even remotely be predicted then it’s real-world random if not scientifically random. It’s not useful to describe it as ‘random’, because it leads to grave misconceptions - and people end up asking “how come it looks so directed?” (or worse). Evolution looks like it is trying hard to produce fit-for-purpose solutions because those solutions that are not fit for purpose, nature deals with brutally and dispassionately. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [October 16, 2013, 11:27am UTC](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280/40 "2013-10-16T11:27:17Z")
> [@Dorjan](#): > > For the most part, you’re only seeing the successes. On a related note - I can’t recall if it’s Dawkins or Gould who emphasised that the visual tree metaphor we have for evolution, especially in scientific illustration, which emphasises the successful branches, prunes off the unsuccessful lineages without regard to their lifespan, and is overall arrayed in a distinctly hierarchical fashion (mammals-\>primates-\>apes-\>humans inevitable being the topmost branch) is part of the overall problem of people’s misconception, and a forest, with the survivors just being particularly tall trees is a better metaphor. I have noticed that the circular rootless dendrogram is becoming increasingly common for lay illustrations too. [Previous page](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280.md?page=1) [Next page](https://boards.straightdope.com/t/why-does-evolution-look-so-directed/671280.md?page=3)