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Our future, our universe, and other weighty topics


Friday, August 21, 2015

Does Darwinism Plausibly Explain the Origin of Human Intelligence?

Probably the three greatest origin mysteries are the origin of the universe, the origin of life, and the origin of human intelligence. Scientists have no explanation for the first of these mysteries, for the Big Bang is unexplained under current science. Darwinism offers no answer to the second of these mysteries. We cannot at all explain the origin of life through any theory of natural selection, as natural selection requires life to exist before it can begin.

But Darwinists claim to have an explanation for the third of these mysteries, the origin of human intelligence. They claim that human intelligence arose because of natural selection. Natural selection involves traits becoming more common in a species when such traits make members of that species more likely to reproduce, or survive until reproduction. A simple Darwinian account of the origin of human intelligence would be that our ancestors got smarter and smarter because there was a survival value in increased intelligence, and natural selection tends to favor traits that give a survival value.

But there are reasons for doubting the plausibility of such an explanation. One reason is that the human mind seems to include many characteristics that do not make a human more likely to survive until he reproduces. Such traits include spirituality, moral reasoning, introspection, self-awareness, altruism, philosophical ability, aesthetic appreciation, and mathematical reasoning.

Another reason for doubting the plausibility of a Darwinian explanation for human intelligence is one that may be called the “high-hanging fruit” reason. This is the reason that the evolution of intelligence in a species would seem to be a case of nature following a path to reproductive success vastly more difficult than easier, simpler paths to reproductive success, which would be rather like someone plucking a fruit from the upper branches of a very tall tree, rather than plucking a fruit from the lower branches. Imagining such a thing does not seem very plausible.

To clarify what I am talking about, let us consider the options available to evolution after some evolutionary ancestor of man descended from the trees, and began life on the ground. We can imagine a variety of options that evolution might have taken to help guarantee reproductive success. They include some of the following:

Evolve a greater sense of smell. Such an adaption (which we can see in organisms such as dogs and bears) is extremely useful in finding food.
Develop claws. Such an adaption (which we can see in bears) can be a powerful weapon against predators when combined with a powerful forelimb.
Develop a large thorax with very powerful arms. Such an adaption (which we see in gorillas) can be a powerful defense against predators.
Develop legs longer and faster than human legs. We don't know of any primate that developed such an adaption, but it would have been very useful in evading predators.
Develop digestive enhancements. We can easily imagine some evolution of the digestive system which would have allowed a species to eat a wider variety of foods (including grass), which would have made finding food a much easier task.
Develop a shorter reproductive cycle, with more offspring. This approach to reproductive success would have been rather the opposite approach of developing intelligence. Instead of evolving a larger brain (which limits the number of offspring, and often involved death to the mother in childbirth because of the difficulty of fitting a large head through the birth canal), a species could have evolved in a way that might that might have led to far more child births per mother, with shorter gestation periods.
Develop camouflage. We can easily imagine an adaption that might have made human ancestors less likely to be noticed by predators, perhaps something like a greenish fur.
Develop better vision. Such an adaption (which we see in eagles, who have 20/4 vision much better than ours) would have made it much easier to find food.

These are only some of the possible adaptions that a human ancestor might have taken to increase its reproductive success. All of these adaptions have one thing in common: they all would have been vastly easier for evolution to have achieved than the evolution of intelligence. Darwinism tells us that the more complicated an adaptive trait is, the more mutations it required. Science has absolutely no specific account of the number of mutations needed to develop human intelligence, but we can be quite sure that the number of mutations needed to develop human intelligence must have been many times greater than the number of mutations needed for the evolution of adaptions like those listed above.

All of the items listed above are rather like low-hanging fruit available to evolution. So why did evolution (when dealing with man and his near ancestors) pass over such possibilities, and instead produce human intelligence, a fruit hanging so much vastly higher up on the tree? It's rather like a hungry person climbing  25 meters up a tree to pluck an apple, rather than just plucking an apple hanging 5 feet off the ground. 

Why did evolution pluck the high-hanging fruit rather than the low hanging fruit?

Limiting ourselves to Darwinism, we cannot at all answer this question by suggesting some kind of “arrow of progress” in evolution by which it favors grander and grander designs. According to Darwinian accounts, natural selection doesn't care a whit about “progress,” but cares about nothing but reproductive success.

Let us imagine that we discovered a planet on which there was some animal species that used laser beams to zap its prey -- laser beams fired from some biological structure of the species. It would be all but impossible to explain such a thing through any account involving natural selection. We could not plausibly explain such a thing merely by saying that such an adaption increased the survival value of the species that had it – because we would still have the question of why such a hard-to-achieve result had been obtained by evolution rather than some other simpler adaption which would have achieved the same degree of survival advantage in a way that would have been so much easier to achieve. Exactly the same problem exists with explaining the origin of human intelligence by using an explanation of natural selection.

What I am suggesting here is that according to Darwinism, the evolution of intelligence is not at all something that we should expect, but is instead some strange fluke. Exactly the same thing has been suggested by some of the leading evolutionary theorists. George Gaylord Simpson wrote an essay called “The Nonprevalance of Humanoids,” suggesting that the evolution of beings like us was some rare fluke we should not expect to see repeated in the accessible universe. Ernst Mawr (another leading Darwinist) argued that the appearance of intelligence was a rare fluke, and that it is highly unlikely that alien life has achieved intelligence.

Comments such as these by leading Darwinists strongly suggest that Darwinism does not offer a plausible account of the origin of human intelligence. Generally speaking, you only offer a plausible explanation of something when you offer some explanation under which such a thing is likely.

Consider a trial in which the prosecution is arguing that someone named John killed his wife. Imagine if the prosecution shows that (a) John had a violent temper; (b) John had $500,000 in gambling debts which he owed to a crime syndicate; (c) John had a million dollar life insurance policy on his wife; and (d) John had just become enraged after finding out his wife was committing adultery. This would all add up to a good start in a plausible case for showing John killed his wife. Under such conditions, we might expect that someone like John would have killed his wife. But imagine the prosecution merely suggested that it was some strange fluke, and that John had killed his wife just because he didn't like the clothes she was wearing on the day she was murdered. That would not be a plausible explanation for a murder, because it would not be a set of conditions under which such a murder would be likely.

Similarly, if Darwinists cannot give us a situation under which the evolution of intelligence is likely under Darwinist principles, they have not provided a plausible explanation of the origin of human intelligence. You do not give a plausible explanation of something if you describe it as being a strange rare fluke under your theoretical framework, something we would be unlikely to see again on any of millions of other planets.

This difficulty was recognized by Alfred Russel Wallace, who developed the theory of evolution at the same time as Darwin. Talking about the human brain (which is about three times heavier than a gorilla brain), Wallace wrote the following (quoted in section 5.8 of this interesting work):

A brain one-half larger than that of the gorilla would....fully have sufficed for the limited mental development of the savage; and we must therefore admit that the large brain he actually possesses could never have been solely developed by any of those laws of evolution, whose essence is, that they lead to a degree of organization exactly proportionate to the wants of each species, never beyond those wants...Natural selection could only have endowed savage man with a brain a few degrees superior to that of an ape, whereas he actually possesses one very little inferior to that of a philosopher.

Upon reading this passage, Darwin wrote to Wallace: “I hope you have not murdered too completely your own and my child.” Darwin need not have worried about such an objection murdering the whole theory of evolution, but should indeed have wondered whether it threw doubt on the idea that natural selection is the main cause of evolution. 

We need to start pondering explanations of the origin of human intelligence which describe a situation under which the appearance of human intelligence is a likely event rather than some incredibly improbable fluke. No theory that describes the origin of human intelligence as some strange improbable fluke can claim to have offered a plausible account of the origin of human intelligence.