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I've been debating this topic with a friend of mine and we can't get to a common answer. She argues that we don't descend from any Chimpanzee or Orangutan because, if we did, they would also have the cognitive thinking ability that we have. I am arguing that a high protein diet allowed the first humans to have the possibility to develop a higher memory, intelligence and other mental procedures.

But after all, what would be the real origin of the intelligence? And if animals do have intelligence too, why isn't theirs as advanced as us.

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Read We did not evolve directly from chimpanzees or orangutans, but rather humans and chimps share a common ancestor more recently than most other species. – Amory Jul 30 '13 at 17:52
Ok, but what about cognitive thinking? – Eric Frick Jul 30 '13 at 18:05
Could you make it clearer as to how these arguments can't coexist? It seems to me that (hypothetically) we could or could not have a common ancestor with chimpanzees and have become more intelligent thanks to a higher protein diet. – rg255 Jul 30 '13 at 18:06
You're right. The main debate here is the origin of the thought. She replies that thinking is a faculty of the soul, and not a matter of biological evolution. My question would be, When does in the line of evolution humans/primates started to actually think. And why ? – Eric Frick Jul 30 '13 at 18:12
I feel that a tighter set of definitions could help the discussion. What do you mean with thinking, cognitive thinking and intelligence? Intelligence/thinking is also not (in my mind) an on/off thing, and there is a continuum between 'pure' instinct behaviour and behaviour based on intelligent thought. Also, if your friend has the starting point of a mind(soul)/matter separation (dualism), where evolution cannot affect the mind, you will probably have a hard time convincing her. – fileunderwater Jul 30 '13 at 18:25

1 Answer 1

How is

  • "we don't descend from any Chimpanzee or Orangutan because, if we did, they would also have the cognitive thinking ability that we have"

not equivalent to

  • "We are not related to the chimpanzee or orangutan because, if we did, they would also have [the same amount of body hair]/[the same sized mouths]/[the same muscular strength] that we have"


Any related species are going to differ in some respects (otherwise they would not be different species, after all), and it is plain to see that intelligence is one of the ways in which species can differ.

Regardless of that (if your friend thinks intelligence is special in a way that hairiness is not), you can make your argument even while sticking to talking about intelligence, and there is no need to go into the reasons for changes (increases) in intelligence to see that.

To make the point with your friend, it might be best to point to two different animals that

  • she recognizes as related, and that
  • she also recognizes as having different levels of "cognitive thinking ability".

In light of such an example, her argument falls flat (unless she further considers only human thinking ability special, in which case you will have a harder time!)

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All the evidence suggests that we aren't qualitatively different from other animals - most of our cognitive traits are present to some extent in other animals. For example, birds, primates and cetaceans can all solve abstract puzzles, and some aniamls apparently recognise themselves in a mirror. – atrichornis Jul 31 '13 at 14:50
Regarding self-recognition:… fact, according to the same wiki article, humans aren't capable of recognising their own reflection until around 18 months. By your friend's logic, do babies therefore have no soul? – atrichornis Jul 31 '13 at 14:51
@atrichornis Nice. I was going to link to exactly that article. +1 (at)Eric Frick, the fact that the list of animals who recognize themselves in the mirror is non-zero should be enough, but let's also consider that self-awareness can be present without understanding of the specific concept of image reflection, so the list is longer still. Also, people who have their sight restored after being blind from birth can fail the mirror test, so your friend can't dismiss atrichornis' baby argument purely on the basis of babies not having all of their cognitive faculties yet. – A.M. Jul 31 '13 at 16:04
@EricFrick The second part of my answer, which admittedly will probably not move your friend, is that the onus is on her to prove the existence of the soul, or that human thinking means a soul is there. On that second part, if she does not want to end up concluding that some humans don't have souls, she will have trouble defining thinking that is present in all humans (including those with severe disabilities) but no animals (including the clearly intelligent ones). – A.M. Jul 31 '13 at 16:26
Indeed. It seems the soul must be a temporary gift. It is given to toddlers who then become self-aware, and then taken away from a proportion of the elderly population who then sink into dementia and lose most of their higher cognitive function. Makes perfect sense! – atrichornis Jul 31 '13 at 16:45

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