Monday, June 15, 2020

Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes, by Nathan H. Lents (author), L.J. Ganser (narrator)

Highbridge, January 2018

Nathan Lents gives us a lively and interesting look at some of the major flaws of the human body--starting with our eyes, and working downward. Our lenses are backwards. Our wrists and ankles have extra, unnecessary bones that serve no real function. We have a variety of genetic diseases, more than most other species, and they don't get effectively selected against for a variety of frustrating reasons. Once a gene acquires a mutation, it tends to accumulate more mutations. Once that happens, the problem can't be fixed by another single mutation of the kind that caused the original problem. The deletion of our ability to manufacture our own vitamin C, like most mammals, got deleted in a common ancestor of primate species long ago. It wasn't selected against because all the early primates lived in the midst of a vitamin C-rich food supply. That mutation has been accumulating more mutations since long before genus homo arose. We're not getting it back.
Others are even more frustrating. The mutation that causes sickle cell anemia causes a devastating, painful, deadly disease--if you get two copies of that gene, one each from father and mother. It ought to have been selected against long ago! Oh, except for one inconvenient fact. If you get only one copy of the disease, you have a higher than normal resistance to malaria. Malaria can also debilitate and kill you. Someone who has one copy of the sickle cell gene doesn't get sickle cell, and is less likely to get malaria, and more likely to survive malaria if they do. In regions where malaria is a major problem, people with one copy of the sickle cell gene will be more likely to live long enough to have more offspring, and thus more descendants--even though some of them will have sickle cell anemia due to getting two copies of the gene.

Nor are we really fully adapted to walking upright, or to giving birth to children with such large brains. Our babies are born several months earlier than they "should" be, based on the degree of development they have at birth, even compared to our closest relatives, the common chimpanzee and the bonobo.

I can't do credit to Lents' writing of this, or to L.J. Ganser's  reading of it. It's informative and enjoyable.


I bought this audiobook.

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