In her blog, On the Wild Side, for the New York Times, the science writer Olivia Judson came right out and said it. She let the cat out of the bag and spilt the beans in a hissing, scratching, slippery mess. Here is how she put it:
It always happens the same way. A glance around the room to make sure no one else is listening. A clearing of the throat. A lowering of the voice to a conspiratorial tone. Then the confession.
“I’ve never read On the Origin of Species. I tried, but I thought it was boring.”
Thus, a number of eminent scientists — biologists all — have spoken. Or rather, whispered.
In this important company I will admit it. I have never read The Origin from cover to cover, although Ruth Hund has - I saw her do it, often on a bouncing boat, and in the actual Galapagos. Remarkable.
I have read large chunks, but I skipped and picked, nodded off and jerked awake, set it down for a year, and picked it up again on January the first. But as with many other new year’s resolutions, my noble attempts often petered out as I looked longingly at a new and unread Oliver Sacks or David Quammen (to say nothing of Ian Rankin, Ruth Rendel, Elizabeth George and even J.K. Rowling). The problem with The Origin is that there are places where Darwin launches into speculations about how things might have worked, what mechanisms might be involved etc., where in hindsight we now know the actual answers. These parts can be a bit tedious at best, and sometimes downright confusing. This is why I skipped about. What is needed is an annotated Origin of Species with lots of explanations, instructions that if you like, the next few pages can be left unread, and background notes. The background notes can be fascinating, and I offer a couple.
Gregor Mendel was the Austrian monk who became the father of genetics with the discoveries he made in the mid 19th century breeding pea plants. He outlined mechanisms for inheritance that have stood the test of time. He knew nothing about DNA, meiosis, chromosomes or genes, but his observations might have given Darwin ideas for a way that characteristics could be passed from one generation to another. Since Darwin reasonably assumed that a mating mixed the characteristics of the two parents together in a sort of soup of information, it was probably hard for him to imagine how a specific trait might emerge unblended in offspring. And of course the concept of mutations was unknown to him.
Suppose a very furry beast mated with another whose coat was sparse and suited for a warm climate. Darwin’s unstated logic would have the offspring with medium coats, while what might actually happen could be a wide spectrum of coat textures. This is because there might be a number of genes associated with fur type. One might, for example, determine how close together the hairs grew, another their length, still another, the hair shaft diameter. In the mating “dice are thrown,” and coat type will depend on which assortment of genes an individual gets, some from the mother, some from the father. A chance combination of genes for closely packed, long, thick hairs would produce a coat suitable for the arctic. Darwin knew that one of the key facts responsible for survival of the fittest was that not all of the offspring from a mating were exactly alike. There was variation that made selection, either by a breeder or by the environment, possible. Had he known about Mendel’s work he would have had the mechanism for natural selection at his finger tips.
So I find it fascinating that Mendel actually sent Darwin a copy of his paper on inheritance in peas. After Darwin’s death the paper was found amongst his affects with its pages uncut. Darwin had never read it. He must have set aside the obscure work written in German in order to get on with his obsessive interest in barnacles. Or perhaps he was doubled over with an attack of one of the assorted nasty symptoms of Chagas disease, a souvenir of his South American adventures. I see him in his study, Mendel’s paper in hand. He grunts, clutches his stomach and rolls his eyes in pain as the parasite extends its invasion within his body. The Austrian monk’s paper slides from his fingers to the floor, to be picked up later by a helpful daughter and tucked amongst other papers, lost and forgotten. This is the sort of detail that for me would make The Origin of Species come alive.
Ask someone (I suggest one of my students) to speculate about why keeping a cat might produce more successful and varied wild flowers in the fields and hedge rows that surround your country cottage – assuming you have one. The brows furrow, and a head is scratched beacuse the connection is not obvious. Darwin explains it. The cats eat mice, the mice usually eat bumble bee honey comb, without the hungry mice, more honey is produced and more bees fly, more flowers are cross-fertilized, more and more varied seeds are produced!
Darwin was astonished by how tame the Galapagos species are. Mocking birds will sit on your foot to peck at a shoelace. Sea lions stroll (actually lumber) into restaurants, sit on park benches and sniff you as you lie on the beach. They show no fear. Darwin threw a marine iguana back into the sea over and over again, marveling how it just climbed back out to approach him. Why are they so tame? One possible explanation suggests that fearfully running away uses energy. If there is no threat, then energy is wasted in this behavior. So there was a selective advantage to not wasting this energy in an environment where there were no threats or predators. This was the situation for millions of years in the Galapagos Islands.
I was interested to read about Dmitri K. Belyaev the other day. He was a Russian geneticist who worked in Russia during the time of the screwball charlatan geneticist Trofim Lysenko. This was after their revolution during the years 1934 to 1960. The thought that the shaping of one's offspring was influenced by one's hard work rather than heredity was appealing. Lysenko believed in the inheritance of acquired characteristics - (cutting the tails off mice should produce tail-less mice. Obviously he never tried it!). It would follow that socialist ideas and behavior would change future generations, getting rid of bourgeois and fascist instincts to produce the ideal communist state. Biologists who followed Mendel's teaching were purged (killed!). So Belyaev had to be very careful with his experiments, and the results of his “secret” work were unknown outside Russia until recently. He bred foxes, artificially selecting them into two breeding groups - those who were fearful and aggressive, and those that were less afraid. The aggressive ones were made into hats. In ten years he produced a breed of foxes that were as calm and friendly as dogs. They also had floppy ears, smaller teeth, coloured coats, thinner bones, and curved tails. They were so pleased and excited to meet humans that they would roll on their backs and pee. So an unnatural selection pressure (humans) had created a fearless breed of foxes in ten generations or so, not millions of years. And energy conservation had nothing to do with it.
A theory for what was actually going on in this selection process by the fox breeder is as follows: What they were actually selecting for were foxes whose adrenal gland development was arrested early in the growth of the embryo's neural crest. The adrenal glands are responsible for the production of adrenalin and the "fight or flight' response in animals. The neural crest of the young embryo contributed to the formation of the adrenal glands, but also jaw and teeth formation, the cartilage of the ear, their bone diameter, coat colour and tail formation. So Belyaev had inadvertently selected for characteristics that produced foxes who didn't fight or flee, but were permanent puppies, a Peter Pan effect. The domestication of dogs and, who knows, perhaps other farm animals, may have followed similar routes.
Now what about those Galapagos animals. If they didn't need to run away from predators, if fighting and fleeing were not important traits, then when natural selection chose those who didn't waste this energy it might also have selected for juvenile "puppy" traits, just like the foxes. Do sea lions demonstrate juvenile behaviors? Well the females play a lot, and it is my observation that their key goal in life is to "get cozy," so perhaps they do. What is needed is a careful comparison of a full range of characteristics shared by California and Galapagos sea lions. The California cousins are aggressive. I wonder what other traits differ?
So reading The Origin can get one thinking. The book selects its readers, stimulating some while boring others. If you stay with it, the nuggets may connect with other things you may have been reading, and the next thing you know a grant proposal might emerge. I volunteer to compare those sea lions species. I love them. I could watch them roll around in the surf all day. In fact I just spent three weeks essentially doing just that. Next year I intend to take binoculars, a notebook and a pencil. Then I’ll have to visit California for a while…
Thank you Charles Darwin.