"We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time."
Curiosity is a virtue, and we should cultivate virtues. It's exciting that we live in an era when explanations for many of the most fundamental aspects of human existence are within reach. In particular, many age-old puzzles have been tackled using evolutionary arguments; for many more, we have tantalising hints and hypotheses but not full explanations. Below I've listed some questions in the latter category. Of course, a set of behaviours often has multiple advantages, and there may be no definitive way to weigh their relative contributions to its evolution. But I think it's likely that in many cases, compelling explanations will be found eventually; until then, it's worth reviewing some of the leading hypotheses.
- A "false alarm" mechanism to reduce tension within groups?
- A social bonding device? (e.g. a replacement for grooming in primates?)
Why do we age and die?
- The inability of natural selection to weed out pleiotropic genes?
- A population control mechanism?
- A group bonding mechanism?
- A mating strategy?
- Byproducts of the abilities to synchronise movements and notice subtle sounds?
- A way to intimidate predators and induce an altered state of consciousness?
Why are humans instinctively monogamous?
- Requirement for men to defend against infanticide?
- A dominant mating strategy given larger social groups?
- Or are we simply not?
Why do we find art attractive?
- A side effect of adaptations which make us find bountiful landscapes and healthy humans aesthetically appealing?
- As a status signal?
Why is there an instinct towards religion?
- A byproduct of other traits such as being able to form theories of mind and causal narratives?
- A group bonding mechanism which helped social hierarchies scale up to larger groups?
Why do we sleep and dream?
- To maintain the efficiency of our synapses, and remove accumulated neurotransmitters?
- To reduce unnecessary and dangerous activity?
Why do fetishes exist?
- Accidental cross-links between neighbouring areas in the human brain?
- Skewed learning of sexually desirable features during childhood?
- Standard mating strategies, simply amplified?
Why do women become infertile long before death (unlike almost all other mammals)?
- The "grandmother hypothesis" that it's more effective to care for grandchildren than having more of your own?
- So that they can be group leaders and repositories of knowledge?
Why does homosexuality exist?
- Kin selection, with homosexuals better able to care for relatives' children?
- Compensatory advantages of the relevant genes (e.g. making heterosexuals with those genes more attractive)?
- The fact that historically, homosexuals have had children at reasonably high rates?
Are (low rates of) autism and depression evolutionarily favourable adaptions?
- Historical roles for autistic people in more specialised occupations?
- Depression as a side effect of selection for neuroticism?
- Depression as a way to focus attention and social allies on a pressing problem?
How did altruism evolve?
- Mainly driven by kin selection?
- As well as socially-enforced reciprocity?
How did life begin?
- In tidal pools on volcanic islands?
- In hydrothermal deep-sea vents?
- Starting from RNA?
Those are all puzzles which hopefully will have a lot more light shed on them in the coming decades. Then there are the mysteries. I think of mysteries as big questions that we don't know how we could discover the answers to, even in principle. Before the theory of evolution, almost all of the questions above were such mysteries. Today, there are only a handful:
How did we evolve to use language?
How did we evolve to use language?
What is consciousness?
Why did the universe begin?
Why does maths work?
Is asking all these questions and learning all these explanations actually useful? Probably not. But think about how amazed our ancestors would have been that we're this close to figuring out answers to questions that seemed so intractable for so long. That sense of wonder, at least, is always worthwhile.