Good evolutionary science
Posted by RyftJun 11
In a recent article from Science Daily [1] we find a compelling bit of science. Evidently the thinking is that humans became the ‘hairless ape’ we are because we evolved in a really hot region in East Africa. You see, the need to “stay cool in that cradle of human evolution may relate, at least in part, to why pre-humans learned to walk upright, lost the fur that covered the bodies of their predecessors and became able to sweat more,” Johns Hopkins University earth scientist Benjamin Passey said. [2] These constituted an “evolutionary advantage” these pre-humans gained. What I find curious, however, is in what intelligible sense this granted an evolutionary advantage when other fauna in that region or similar climates supposedly evolved just fine, walking around on all fours and covered in hair, etc. (picture animals like buffalo, wolf, baboon and such).
Surely the Panthera genus had even more selection forces acting upon them, being not only covered in fur but walking around so close to the ground (which radiates absorbed heat, so they get cooked on both sides). What do you suppose they think of this robust evolutionary science?
- Johns Hopkins University. “Some Like It Hot: Site of Human Evolution Was Scorching.” Science Daily, 8 June 2010 (Accessed 10 June 2010.)
- Benjamin H. Passey, Naomi E. Levin, Thure E. Cerling, Francis H. Brown, and John M. Eiler. “High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates.” Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1001824107
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13 comments
Comment by tavarish on 11 Jun 2010 at 05:34
I’m sorry, I don’t understand how this is a facepalm. You’re essentially saying “Why aren’t apples oranges when they grow in the same region?”
It’s a nonsensical argument, and you’re completely missing the point of how evolution by natural selection works. Different species have different physical traits, intelligence, diets, status in the food chain, methods of shelter and safeguarding, and instincts. All of this, coupled with chance, plays a part is what shapes natural selection in a given region. This dictates an animal’s environment, not solely the region in which it resides in.
It does not follow that other animals should have to shed its fur because humans did, as they don’t abide by the same environmental criteria, nor would it be reasonable to ask that they do. It’s like asking why panthers didn’t develop tools for survival. Their environment didn’t require it for their survival (at least not to the extent as humans did).
The only thing facepalm worthy is this blogpost.
Comment by Rene Mulder on 11 Jun 2010 at 09:39
Luckily we ‘evolved’ back to having full body hair when we spread to the cold regions of the world. Or wait…we didn’t :P
It just doesn’t make sense to make such a critical ‘evolutionary’ error. What back-up would you have when things’d turn cold?
Silly.
Comment by Ryft on 13 Jun 2010 at 17:13
It would be nice if for once, Fred, you didn’t build meticulous straw men to tear down. You have an impressive resumé of refuting arguments but (at least in our interactions) they are almost never the arguments your opponent actually makes. Here, like so many places elsewhere, you completely missed the point I was making. This was not an academic critique, and it baffles me how anyone could confuse it as one. If only you had requested clarification, instead of quixotically battling your own straw men.
This was a sardonic (derisive humour) lament over how a perfectly good bit of science—research into the temperature of soil carbonates during initial formation for falsifying earlier theories about the East African environment during the Pliocene and Pleistocene—was ruinously littered with just-so evolutionary fairytale nonsense, as if the sun made hominids lose all their hair and start sweating. Why they have to infect respectable scientific research with such embarrassing unscientific twaddle is simply bewildering. Hence, my “disdainfully or skeptically humorous” lament.
For more information, see here.
Comment by tavarish on 13 Jun 2010 at 18:51
Either we’re not reading the same article or you don’t have an understanding of what the article actually entails.
Do you really think panthers that didn’t have identical evolutionary steps in a similar region mean that this theory is unscientific?
Comment by Mark William on 14 Jun 2010 at 10:50
No, it wasn’t “ruinously littered with just-so evolutionary fairytale nonsense.” As the article says, it has implications for the development of human thermophysiology. The hypothesis has been for some time that a hot environment could have been the selection force that caused these evolutionary changes. This finding, if true, strengthens that hypothesis and is good science.
You falsely assume that nature had only the sweaty, hairless, bipedal route to take to deal with regulating internal temperature. This is false. The Panthera genus, as with others, simply became nocturnal.
You also ignore the importance of fur as protection for and from predators. Other methods such as scales or thick hide were used; however, once nature had taken one of these routes it could not select against it, unless the roles of prey and predator changed, as it did for human ancestors. They developed different strategies for hunting and avoiding predators. These strategies worked best in the day where their intelligence could make use of the increased information offered by daylight. Then it became more important to select for a thermophysiology that allowed them to be diurnal in a hot climate.
Comment by Ryft on 14 Jun 2010 at 21:36
“Either we’re not reading the same article or you don’t have an understanding of what the article actually entails.”
This is the correlative based fallacy known as bifurcation (i.e., false dilemma), in which only two alternatives are presented when in reality there may be more. This fallacy may be overcome by simply giving consideration to additional options—which clearly Fred himself did not bother to do here, by accident or design. But this is a concern only for those who care about valid reasoning or argumentation, and only Fred can speak for himself in that regard. It is also interesting to note that Fred does not admit any culpability; both options in this false dilemma conveniently lay the fault at my feet alone, a trick used by sophists to colour their opponent. Notice, too, that in either case Fred is addressing the arguer instead of the argument.
“Do you really think panthers that didn’t have identical evolutionary steps in a similar region mean that this theory is unscientific?”
First, I am not sure that panthers in East Africa are relevant to this discussion because, according to current speculation, they did not appear on the scene until long after the time period in human evolution this discussion considers, a time period in which it is thought the Panthera genus itself was just beginning to evolve (Pliocene and Pleistocene epochs). I had to look that up because I was willing to give Fred the benefit of doubt and regard it as a typo (that he typed "panthers" but meant "panthera").
Second, it is all quite irrelevant at any rate because nowhere in anything I have written is it indicated that I thought, much less really thought, that the evident difference in “evolutionary steps” between the Panthera and Homo genera is what makes this theory unscientific. This is a blatant straw man of Fred’s own construction. I cannot reasonably be expected to defend an argument that is not mine, especially one fabricated out of thin air that no one in this conversation holds.
Comment by Ryft on 14 Jun 2010 at 21:37
Mark William,
Does East Africa being hot during the Pliocene and Pleistocene epochs have implications for the evolution of thermoregulation in humans? Yes, especially when you consider that it has long been thought the African climate in this region during that time period was cooler than what Passey found (nota bene: cycles of continental glaciation). As I already said, Passey’s work was indeed good science, as research into falsifying popular theories about the climate in East Africa during these epochs.
But what I find particularly troubling is this notion that "a hot environment could have been the selection force that caused" the evolutionary changes in human thermoregulation. First, there are various units of selection that operate under the neo-darwinian synthesis but, consistent with the mechanisms of evolution, they are all biological forces. (According to Bowler [1984] and Dawkins [1976] the gene is the only true unit of selection.) What causal mechanism is scientifically proposed by a hot climate? At best one could reference population behavior to such climates, but then the unit of selection is not the climate, is it? Second, what hypotheses on the evolution of thermoregulation in humans have a hot climate as one of its testable predictions? You see, the only way Passey’s work could "strengthen" such hypotheses is if they made a prediction that his work either falsified or corroborated.
And no, I did not "assume that nature had only the sweaty, hairless, bipedal route to take to deal with regulating internal temperature." That is your own straw man, constructed out of deeply misunderstanding not only the point my article was making but also the extent of my knowledge of modern evolutionary synthesis. Both misunderstandings, I suspect, were predicated on a stereotype of Christians; i.e., since I am an opinionated Christian who blogs, I must be a Young Earth creationist who is clueless about evolution. It is the only way that your response makes sense; in other words, you would not have responded the way you did if you had adhered to the principle of intellectual charity and assumed your opponent was properly and sufficiently informed. I would encourage you to practice that principle in the future, as it is very effective for avoiding straw man fallacies (i.e., assume the best about your opponent, not the worst).
Comment by Adam on 15 Jun 2010 at 14:25
This sounds suspiciously like Lamarck’s theory of evolution which is based on the idea that individuals adapt during their own lifetimes and transmit traits they acquire to their offspring. Offspring then adapt from where the parents left off, enabling evolution to advance. Lamarck’s theory was thoroughly refuted in 1889 by German biologist August Weismann. He showed that Lamarck’s explanation of evolution was incorrect. Weismann cut off the tails of hundreds of mice for 22 generations. Lamarck’s hypothesis would predict that eventually mice would be born with shorter tails or no tails at all. However, Weismann’s mice continued to produce baby mice with normal tails. Weismann concluded that changes in the body during an individual’s lifetime do not affect the reproductive cells or the offspring. There appears to be no link between the reproductive cells and the rest of the body. Any variant in an individual due to environment will not be passed on.
Comment by Ryft on 15 Jun 2010 at 17:54
Bingo.
Comment by tavarish on 15 Jun 2010 at 21:25
Oh, I understand. You guys seem to think that the article is an appeal to Lamarckian evolution rather than Darwinian.
Here’s an excerpt:
“That hypothesis states that our pre-human ancestors gained an evolutionary advantage in walking upright because doing so was cooler (when it is sunny, the near-surface air is warmer than air a few feet above the ground) and exposed their body mass to less sunlight than did crawling on all fours. The loss of body hair (fur) and the ability to regulate body temperature through perspiration would have been other adaptations helpful for living in a warm climate, according to the hypothesis.”
Where does that say anything about learned traits transmitted via heredity? It simply says that having traits such as these would be evolutionarily advantageous in the environment.
How this is apparently a facepalm, I still don’t understand.
Comment by Ryft on 15 Jun 2010 at 21:31
“How this is apparently a facepalm, I still don’t understand.”
Then you haven’t understood my responses (to you and Mark William).
Comment by tavarish on 16 Jun 2010 at 05:13
Thanks for being specific.
Comment by Duane on 16 Jun 2010 at 16:28
Tav (or Fred?),
I don’t know if your Lamarckian/Darwinian dichotomy is helpful?
Lamarckian evolution says that acquired characteristics resulting from certain behaviours or environmental conditions can be passed on to offspring. Now it seems to me that Darwin’s theory of pangensis is very much Lamarckian in principle, so it doesn’t help at all to try and contrast Lamarckian evolution with Darwinian evolution.
Neo-Darwinian evolution on the other hand might provide the better comparison, where changes in traits are understood to have been acquired from mutations in the genome and then expressed in the phenotype; the organisms “selected” being those that are best suited to the environment, rather than the environment causing the changes.
Now, Passey is saying that a reason “why pre-humans learned to walk upright, lost the fur that covered the bodies of their predecessors and became able to sweat more,” is out of a need to stay cool. Similarly Lamarck may argue that the reason elephants trunks or giraffes necks got longer was out of a need to reach certain food sources?
So I have to ask myself, in the article to which Ryft refers, is Passey’s driving force behind the alleged evolution of human beings more like the Lamarckian system, or the Neo-Darwinian? As Adam has already said, it sounds suspiciously Lamarckian.
[Edited by Duane: 16th June 2010]