in case if you frown upon the title, I would like to highlight that the author is a biologist, he is neither a saint nor a sinner.
biology as a science has a sort of philosophical completeness that the physics, the most fundamental of all science doesn't possess. biology can answer both "how" and "why" questions. molecular biology and/or genetics do answer the question of "how", for example, they can tell you the step by step process of "how" a living being dies, but they will definitely fail to answer "why" we die at all the "why" questions in biology are addressed by the theory of evolution. if you stuck with any riddle in biology, just ask Mr. Darwin, he has the final say.
physics has quantum mechanics, the theory of relativity and they can satisfactorily answer the question like, how does the subatomic particle interact with each other or how a galaxy is formed. but unlike biology, physics has no theory that can answer the "why" questions, why a particle interact in the way it does or why gravity exists that for the galaxy etc. put it in another way, there is no theory of evolution in physics. but we can imagine, once such "theory of why" emerges in physics, it will face the same resentment as the evolution did.
as the first word in the title implies, this book is on "why" and not on "how". why the human has so distinctive sexual biology than other primates or mammalian species. so far, I've got the opportunity to read five books by Mr. Diamond. they broadly fall under two categories: about human as a species, this book and the "The Third Chimpanzee" belongs to this group. the second category is about human society, "Guns Germs and Steel", "Collapse" and "World Until Yesterday" goes here.
some of the topic in "The Third Chimpanzee" has been discussed in great detail in this book. here two concepts those I couldn't resist sharing as I never thought them in the way they were presented:
beyond any doubt, the brain and the thumb are the key adaptations those changed the fate of human species. Mr. Diamond argued that biologically female menopause is as revolutionary as the human brain and thumb. unlike males, females of human species got their reproductive system shutdown by the age of fifty, while they live several decades afterward, apparently, without any reproductive advantage. why is so
the human birth canal was not evolved to deliver an enormous human fetus or twin, as a woman grows older her mortality due to childbirth increases significantly. a human child requires a long time of nursing and caring before becoming independent, and in old days society couldn't sue a father for refusing his childbearing responsibility. hence as more elderly women died during childbirth, their infants used to follow the same fate of their deceased mother, and genes not promoting the menopause were slowly removed from the gene pool. menopause helped the single mothers to live longer and take care of their babies in early hunter-gather and forager society.
the lesson is that the world we see today wouldn't be possible without single mothers.
the second interesting point was about old people:
before the invention of writing, people used to memorize enormous knowledge about their environment, plants, animals, etc. as they get older, when they could no longer hunt or bring food to their tribes/family. instead of becoming obsolete, they turned into a library. old people were the living libraries in the ancient society, they were valued and honored by their people. it is the invention of writing that took away the job from old people as the librarian and turned them into a social burden.
if you think carefully, biologically humans are good for nothing. not only in childbirth, the humans were not a good hunter, so they opt for foraging, they were not good at foraging either, so they adopted agriculture. as history tells us, the humans were not good even in agriculture, soon they formed civilization and raged war against each other. apparently, they were so bad in the war that they stop their conquest and focused on science & technology. and guess what, even after two hundred years of advanced science and technology humans were found to be worse enough not to figure out "why" question in physics!
isn't it weird