I have 4 books waiting in line for a review. I have been reading but I had no time to write.
Now I am in vacation and I intend to catch up.
I have been reading lots of books on evolution, biology and genetics lately.
This time was The Red Queen by Matt Ridley, a book on Sex and the evolution of Human Nature.
In case you are wondering what does Lewis Caroll have to do with genetics, here it goes.
Red Queen is the name of a theory on evolution that took its name from Caroll’s “Through the Looking-Glass”.
It is named after the chess piece which lives in a strange world where “it takes all the running you can do, to keep in the same place.”
It is a theory about fierce competition between living things which evolve only to see all the other living things evolving just as fast so they have to keep doing it just so they can keep up with their own species, their predators, their parasites, well with pretty much all their environment.
Sex, in his words, is recombination and outcrossing of genes. By recombination, each parent passes on to the offspring 25% of 2 complete sets of genes.
This effectively means half but mixing 2 full sets and discarding 3 quarters makes for a very good shuffle.
The father passes on half of his genes and the mother does just the same and this is the part called outcrossing.
Matt spends a good deal of time explaining that sex as a mean of reproduction is too expensive to occur in nature so it must be something to it.
By the way, in case you are just thinking “well, duh, I do like to have sex so much so it must be a good enough explanation for why it caught on so well” this is wrong.
You like to have sex so much because your ancestors that didn’t like it simply did not survive.
We are the offspring of ancestors who liked to eat, fight and have sex and even more, of those who were good at it. That is to say, we all descend from humans that were good at surviving and at reproducing.
Now, what is there that makes sexual reproduction spread? I already knew that asexual reproduction has a better chance of spreading in direct competition with sexual reproduction, if you don’t take external factors into consideration.
In 1965, there came a theory on how sex brings in more mutations than asexual reproduction (good mutations are rare) so the sexual species are more likely to adapt.
While this is a good explanation, it is also not enough. A shorter lifespan brings more mutations to species too. The problem with this theory is it does not explain how it helps individuals of the same species which are in a direct competition for food and mates. If you happen to have a good set of genes, how does it help you to share it with another individual?
Matt brings in a joke here to help understanding the principle:
Two philosophers are being chased by a bear. One says “Hey, why are we running anyway, we cannot outrun the bear?”
The other replies “I don not intend to outrun the bear, I only need to outrun you.”
Then came another theory that says sex might be derived from an ancient mechanism for gene repair. By recombination, you have a good chance of replacing a damaged gene with a good one from the other full set. Problem with this is it does not explain outcrossing at all.
A good theory on why sex was invented can be that it helps adapt to difficult environment.
But the problem is this theory is not proven by facts. On the contrary, sex is rare in extreme living conditions.
Even more, organisms that have the capability to reproduce n an asexual and in a sexual manner all the same, have been found to choose sexual reproduction when living is easy and asexual when living gets though.
Matt goes on in his quest to find why sex was ever invented. He does not have the final answer, I think.
In my opinion it may be a combination of those reasons he mentioned along the way.
One more I am going to quote here. In a chapter on parasites, he explains that sex increases (in children) the immunity to those parasites that already had time to adapt to the parent’s defenses. The parasites, having a much shorter lifespan will have time during an adult, say, human lifetime to the host immune system defense mechanisms so they have a set of keys for all its doors. Sex is like changing the locks.
I read about beautiful things in this book like the bamboo trees that flower once every 121 years all at the same time. And they all die short after that, as if they want to make room for their offspring. For those who know how dense a bamboo forest can grow, this makes lot of sense. What plant can grow with no light at all? The effect is that the parasites and predators of the bamboo will die along with the trees.
The most sad thing: this leads to a major crisis in the life of panda bears which do not eat anything else.
I read about strange things in this book. I read about mushrooms that have 17 genders. Each sex will be able to combine with all the other except itself.
I read about sexual selection, about polygamy and men, monogamy and women about the sexual mind and the game of finding versus keeping partners.
I learned why women want to be more skinny than the men want them. I read about homosexuality, wealthy men that die alone instead of marrying more women, about sexism and racism.
It is a complete and very well written book. You will enjoy it
The book has 350 pages and you can buy it for around 15$ from your favorite online store.
I strongly recommend it. One of the best I ever read.
As usual I found other books recommended by the author so I will probably read next “Adaptation and natural selection” by George Williams, 1966