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]

Then you haven’t understood my responses (to you and Mark William).

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.

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).

• Bowler, Peter J. (1984). Evolution: The History of an Idea.
• Dawkins, Richard (1976). The Selfish Gene.

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.

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.

Do you really think panthers that didn’t have identical evolutionary steps in a similar region mean that this theory is unscientific?