Darwin and speciation. Charles Darwin wrote a book Origin of Species. His editor asked him to write instead a book on pigeon breeding. The reason is obvious. He devotes an enormous amount of space to the subject, and the passages are truly wonderful. So far as I know, nobody has gone through and seen just how accurate he was. That seems to me to be a pity. Some of his observations are a bit baffling to me. With some, I don’t see how genes could act the way he says.
As far as the origin of species, he only has one sentence. He announces that speciation is happenstance, because hybrid infertility never did any species any good. That is odd, because when he is not talking about his pigeons, he is making the point that the term species is meaningless. He invokes the very concept he is at such pains to discredit in order to explain the mechanism for the subject of his entire book. No wonder he was so gloomy.
Of course speciation is a way to exploit a large and rich environment while reducing the problem of excessive population size. Darwin can be forgiven for not having realized that fact. Not many scientists realize it to this very day. Most of the evidence I can bring to bear consits of meticulous field counts of animals and careful comparison of fertility with relatedness and fertility with marital radius. There is also the UN statistical source. None of these were available to him.
There was evidence he might have consulted. Surely it was obvious that birds traveled in flocks when they migrated. Surely he knew about the competition between male mammals during mating season. These mechanisms limit mating pool size. There might have been enough known about ancient history to see the pattern of how civilizations fail. There is no plausible explanation for the overall pattern except urban infertility, and urban infertility must have been obvious. The big gene pool is the common denominator of urban societies. But since nobody else noticed, it is not surprising that Darwin did not.
But there is another advantage to speciation that he might have thought of. Subdividing a population prepares it to evolve further by not having to involve every member of the population in the change. It seems odd that Darwin did not mention anything of the sort. If evolution is good, then speciation is good. If evolution is inevitable, then speciation is in evitable. If evolution systematically gives organisms an advantage, then the ability to evolve is itself an advantage, and an inherent tendency to speciation is an advantage.
There is a slightly different issue that encourages speciation. No only does it let evolution proceed by letting a number of small groups compete with the advantage going to the group that first evolves into a superior form. It allows for specialization.
We humans are general purpose organisms. Some individuals may have inherent advantages in a limited range. Basketball players and even tennis players find it easier to reach high if they are tall, and this helps in competition. On the other hand, there was a Russian tank design that was so restrictive that a crew member could not be over five foot four and fit in the tank. They can’t have had a very good basketball team. But by and large, barring such artificial constraints, pretty much you can do anything you put your heart into.
The reason we are so good at so many things is evolution. We, as I have said, probably evolved the capacity for true love and in so doing were able to stop supporting an immune system suitable for promiscuity. Then we evolved the cognitive ability to use technology and were able to evolve farther and faster still. We, as it were, looked at a range of possible improvements and bought them all.
But we are exceptional. Most of the time the specialist will surpass the general purpose form. Other animals specialize a lot. Speciation helps you specialize. Absent speciation we would still be blue green algae. There are a few simple life forms that are able to move around and also able to perform photosynthesis. But the overwhelming bulk of visible life either sits still and captures energy from the sun or else harvests energy some other form of life captured. There is an enormous amount of life in the sea floor that is just now becoming understood. Those forms may get some energy from geothermal vents or chemical sources as well as from sunlight. They may be generalists, and they seem to constitute a significant amount to the world’s biomass. Forgive me for not knowing more. But of what we see, specialization rules. And specialization requires speciation.
Technically Darwin is right. Speciation is “happenstance,” that is it happens at random or at least happens because of random mutations. Life is happenstance from a scientific perspective. But the notion that speciation accomplishes nothing, that notion does not wash.
There have been 807 visitors so far.