This is a video of Daniel Lieberman lecturing on "Brains, Brawn, and the Evolution of the Human Body." Lieberman is a proponent of the "endurance running hypothesis"--the idea that our human bodies and brains are evolved for running long distances, because this was required for persistence hunting millions of years ago before the invention of hunting technology like bows and arrows.
The arguments here by Liebenberg and Lieberman help to resolve a paradox about human evolution first identified by Alfred Russel Wallace. While Wallace was a co-discoverer along with Darwin of the theory of evolution by natural selection, Wallace disagreed with Darwin in that Wallace did not believe that natural selection could fully explain the evolution of human beings in their high moral and mental capacities. In his essay on "The Limits of Natural Selection as Applied to Man," Wallace argued that the human brain was larger than it needed to be for survival as a primitive hunter-gatherer. Natural selection, he observed, "has no power to produce absolute perfection but only relative perfection, no power to advance any being much beyond his fellow beings, but only so much beyond them as to enable it to survive them in the struggle for existence." And yet human beings have mental powers for abstract thought, as expressed in art, science, mathematics, philosophy, and religion, that would not have been useful for the survival of our Paleolithic ancestors. Such powers could not therefore have evolved by natural selection, because they would have been useless for the survival and reproduction of our prehistoric ancestors.
"The mental requirements of savages, and the faculties actually exercised by them, are very little above those of animals. The higher feelings of pure morality and refined emotion, and the power of abstract reasoning and ideal conception, are useless to them, are rarely if ever manifested, and have no important relations to their habits, wants, desires, or well-being. They possess a mental organ beyond their needs. Natural Selection could only have endowed savage man with a brain a little superior to that of an ape, whereas he actually possesses one very little inferior to that of a philosopher."Since the evolution of such a brain could not be the work of natural selection, Wallace inferred, it must be the work of artificial selection by "some higher intelligence." Just as human beings have artificially selected plants and animals to be bred for special traits, so this "higher intelligence" must have guided human evolution to achieve a high mental capacity. Many readers assumed that this "higher intelligence" must be God. But Wallace said this was a misconception, because this higher intelligence could be some kind of spiritual mind other than God.
Creationists and intelligent design theorists have seen Wallace as agreeing with their claim that natural science can see evidence of creative intelligence in the natural world, and particularly in the cognitive and moral capacities of the human mind that show evidence of supernatural design.
Similar to Wallace's argument is the argument of theistic evolutionists like C. S. Lewis and Alvin Plantinga that an evolutionary naturalism becomes self-refuting if it denies the supernatural origin of the human mind. The reasoning is that the theistic doctrine of the human mind as created by God in His image provides the necessary support for the validity of human thought, including the validity of modern science. If we embrace metaphysical naturalism--the view that nothing exists except nature, and so there is no God or nothing like God--we are caught in self-contradiction: if human thought originated not from a divine Mind but from the irrational causes of nature, then we cannot trust our minds as reliable, and thus we cannot trust our belief in naturalism, or anything else. Insofar as science--including evolutionary science--depends on the validity of human thought, and insofar as theism is the indispensable support for trusting in the validity of human thought, science is not only compatible with theism, science depends upon theism.
In my posts on Plantinga's argument (here and here), I have pointed out that the weak link in Plantinga's reasoning for metaphysical naturalism as self-defeating is his assumption that adaptive behavior is completely unrelated to true belief. Plantinga asks us to imagine that we could have been naturally evolved for a state of complete and perpetual delusion. Having taken this step of radical Cartesian skepticism, he then tells us--as Descartes did--that the only escape from such skepticism is to assume that God would never allow this to happen. But as always is the case for the Cartesian skeptic, this all depends on imagining scenarios that are utterly implausible and unsupported by even a shred of evidence. The evidence of evolutionary history suggests that evolution produces cognitive faculties that are reliable but fallible. The mental abilities of animals, including human beings, are fallible because evolution produces adaptations that are good enough but not perfect, and this results in the mental fallibility that is familiar to us.
But despite this fallibility, the mental faculties cannot be absolutely unreliable or delusional. Even Plantinga concedes that in the evolution of animals, "adaptive behavior requires accurate indicators." So, for example, a frog must have sensory equipment that allows him to accurately detect flies so that he can catch them with his tongue. And the honeybee waggle dance is a dramatic example of how evolution by natural selection favors adaptive behavior that tracks the truth about the world.
Similarly, evolution by natural selection has given human beings mental capacities that are reliable, even if fallible, in tracking the world. If Liebenberg is right, the distinctively human mental capacities arose originally among prehistoric hunter-gatherers for the literal tracking of wild game, which created the capacity for the abstract hypothetical reasoning of modern science.
Archaeological evidence indicates that our hominid ancestors were hunting about two million years ago. Without weapons such as bows and arrows, the only effective form of hunting was probably persistence hunting--chasing an animal during the hottest time of the day until it overheated and dropped from exhaustion. Anatomical evidence indicates that human beings are the only primates that are designed for the endurance running required for persistence hunting.
In easy tracking terrain, hunters could follow an animal's trail by looking for one sign after another. But in difficult terrain, the hunters had to imagine the likely route the animal might take so that they might reconstruct the animal's behavior and decide in advance where they might find signs. This would require what Liebenberg calls "speculative tracking" that uses "hypothetico-deductive reasoning." Based on their knowledge of animal behavior and of the physical environment, hunters had to interpret the visible signs of an animal's path in terms of some hypothesis as to how and where the animal was moving.
In modern science, the visible world is explained by a postulated invisible world. So that, for example, physicists use particle colliders to create visible particle tracks that are explained by hypotheses about invisible structures (atoms and subatomic particles) and forces (such as gravity). Similarly, ancient hunters tracking an antelope had to interpret visible tracks as signs to be explained by hypotheses about the invisible movements of the antelope. This abstract mental capacity for hypothetical reasoning could evolve by natural selection because those hunters who were good at this were more likely to have antelope for dinner.
It has been observed, however, that only a few people in hunter-gatherer societies are successful at this, because only the most intelligent members of the society will have the capacity for such scientific reasoning. Similarly, we know that only a few people--an Aristotle, an Isaac Newton, or an Albert Einstein--will have the intellectual capacity for the deepest scientific or philosophic inquiries. And thus the philosophic or scientific life will be most fully expressed by only a few people, even though the capacity for philosophic and scientific reasoning is latent in evolved human nature.
This same capacity for imaginative, hypothetical reasoning that generates scientific and philosophic knowledge can also generate mythic fiction and superstition. Knowledge is valuable, because if we can follow the tracks of the antelope, we find the antelope, and we can eat. We can also derive some satisfaction in telling stories about the antelope deity, although we will never find it.
Bramble, Dennis M., and Daniel Lieberman. 2004. "Endurance Running and the Evolution of Homo." Nature 432 (18 November): 345-52.
Conniff, Richard. 2008. "Yes, You Were Born to Run." Men's Health 23 (May): 132-39. Available online.
Liebenberg, Louis. 2013a. The Origin of Science: The Evolutionary Roots of Scientific Reasoning and its Implications for Citizen Science. Cape Town, South Africa: Cybertracker.org. Available online.
Liebenberg, Louis. 2013b. "Tracking Science: The Origin of Scientific Thinking in Our Paleolithic Ancestors." Skeptic Magazine 18, no. 3: 18-23. Available online.
Wallace, Alfred Russel Wallace. 1870. "The Limits of Natural Selection as Applied to Man." In Contributions to the Theory of Natural Selection: A Series of Essays. London: Macmillan.