THE ASCENT OF MAN

 JACOB BROWNOWSKI

MACDONALD FUTURA PUBLISHERS                        1973

PART XII

 

Chapter 12: Generation Upon Generation

In the 19^th century the city of Vienna was the capital of an Empire which held together a multitude of nations and languages. It was a famous centre of music, literature and the arts. Science was suspect in conservative Vienna, particularly biological science. But unexpectedly Austria was also the seedbed for one scientific idea (and in biology) that was revolutionary.

At the old university of Vienna the founder of genetics, and therefore of all the modern life sciences, Gregor Mendel, got such little university education as he had. He came at a historic time in the struggle between tyranny and freedom of thought. In 1848, shortly before he came, two young men had published far away in London, in German, a manifesto which begins with the phrase: ‘a spectre is haunting Europe’, the spectre of communism.

Of course, Karl Marx and Friedrich Engels in The Communist Manifesto did not create the revolutions in Europe; but they gave them the voice. It was the voice of insurrection. A spate of disaffection ran through Europe against the Bourbons, the Habsburgs, and governments everywhere. Paris was in turmoil in February 1848, and Vienna and Berlin followed. And so in the University Square in Vienna in March 1848 students protested and fought the police. The Austrian Empire, like others, shook. Metternich resigned and fled to London. The Emperor abdicated.

Emperors go, but empires remain. The new Emperor of Austria was a young man of eighteen, Franz Josef, who reigned like a medieval autocrat until the ramshackle empire fell to pieces during the First World War. I still remember Franz Josef when I was a small boy; like other Habsburgs, he had the long lower lip and pouched mouth which Velazquez had painted in the Spanish kings, and which is now recognized as a dominant genetic trait.

When Franz Josef came to the throne the patriots’ speeches fell silent; the reaction under the young Emperor was total. At that moment the ascent of man was quietly set off in a new direction by Gregor Mendel. He had been born Johann Mendel, a farmer’s son; Gregor was the name he was given when he became a monk just before this, frustrated by poverty and lack of education. He remained all his life a farm boy in the way he went about his work, not a professor nor a gentleman naturalist like his contemporaries in England; he was a kitchen-garden naturalist.

• The Austrian Government wanted the bright boys among the peasantry taught by monks.
• He went back in thought to what he had learned on the farm and had been fascinated by ever since: plants.
• Mendel decided to devote his life to practical experiments in biology, here in the monastery.
• The plant that he had chosen, very carefully, is the garden pea. He picked out seven characters for comparison: the shape of seed, colour of seed, and so on, finishing his list with tall in stem versus short-stemmed.

• Mendel had guessed that a simple character is regulated by two particles (we now call them genes). Each parent contributes one of the two particles. If the two particles or genes are different one will be dominant and the other recessive. The crossing of tall peas with short is a first step in seeing if this is true.
• The first generation of hybrids, when fully grown, are all tall. In the language of modern genetics, the character tall is dominant over the character short.
• It is not true that the hybrids average the height of their parents; they are all tall plants.

Now the second step: we form the second generation as Mendel did. We fertilize the hybrids, this time with their own pollen. We allow the pods to form, plant the seeds, and here is the second generation. It is not all of anything, for it is not uniform; there is a majority of tall plants, but a significant minority of short plants. The fraction of the total that consists of short plants should be calculable from Mendel’s guess about heredity; for if he was right, each hybrid in the first generation carried one dominant and one recessive gene. Therefore in one mating out of every four between first generation hybrids, two recessive genes have come together, and as a result one plant out of every four should be short. And so it is: in the second generation, one plant out of four is short, and three are tall. This is the famous ratio of one out of every four, or one to three, that everyone associates with Mendel’s name – and rightly so.

• Life on earth has been going on for 3000 million years or more. For two-thirds of that time organisms reproduced themselves by cell division, producing identical offspring, except for the rare mutation. For all that time evolution was slow.
• Less than 1000 million years ago sexual reproduction begins, first in plants, then in animals. Sex produces diversity, and diversity is the propeller of evolution, all made possible by the emergence of two sexes.
• The multiplicity of shape, colour, and behaviour in individuals and in species is produced by the coupling of genes, as Mendel guessed.
• How the message of inheritance is passed from one generation to the next was discovered in 1953, and it is the adventure story of science in the 20^th century, when James Watson teamed up with Francis Crick to decipher the structure of DNA.
• The DNA molecule is a right-handed spiral staircase with each tread of the same size, at the same distance from the next, and turns at the same rate between successive treads.
• These treads are a code which will tell the cell step by step how to make the proteins necessary for life.

Every cell in the body carries the complete potential to make the whole animal, except only the sperm and egg cells. The sperm and the egg are incomplete, and essentially they are half cells: they carry half the total number of genes. Then when the egg is fertilized by the sperm, the genes from each come together in pairs as Mendel foresaw, and the total of instructions is assembled again. The fertilized egg is then a complete cell, and it is the model of every cell in the body. For every cell is formed by division of the fertilized egg, and is therefore identical with it in its genetic make-up. Like a chick embryo, the animal has the legacy of the fertilized egg all through life.

The baby is an individual from birth. The coupling of genes from both parents stirred the pool of diversity. The child inherits gifts from both parents, and chance has now combined these gifts in a new and original arrangement. The child is not a prisoner of its inheritance; it holds its inheritance as a new creation which its future actions will unfold.

Should we make clones of human beings – copies of a beautiful mother, perhaps, or of a clever father? Of course not. My view is that diversity is the breath of life, and we must not abandon that for any single form which happens to catch our fancy – even our genetic fancy. Cloning is the stabilization of one form, and that runs against the whole current of creation – of human creation above all. Evolution is founded in variety and creates diversity; and of all animals, man is more creative because he carries and expresses the largest store of variety. Every attempt to make us uniform, biologically, emotionally, or intellectually, is a betrayal of the evolutionary thrust that has made man its apex.

• We have to explain the speed of human evolution over 5 million years at most. That is terribly fast. Natural selection simply does not act as fast as that on animal species.
• We, the hominids, must have supplied a form of selection of our own; and the obvious choice is sexual selection.
• There is evidence now that women marry men who are intellectually like them and men marry women who are intellectually like them.
• If that preference really goes back over some millions of years, then it means that selection for skills has always been important on the part of both sexes.

I believe that as soon as the forerunners of man began to be nimble with their hands in making tools and clever with their brains in planning them, the nimble and clever enjoyed a selective advantage. They were able to get more mates and to beget and feed more children than the rest. If my speculation about this is right, it explains how the nimble-fingered and quick-witted were able to dominate the biological evolution of man, and take it ahead so fast. And it shows that even in his biological evolution, man has been nudged and driven by a cultural talent, the ability to make tools and communal plans. I think that is still expressed in the care that kindred and community take in all cultures, and only in human cultures, to arrange what is revealingly called a good match.

• What keeps alive the cultural variety among human beings? The prohibition of incest only has a meaning if it is designed to prevent older males dominating a group of females, as they do in ape groups.
• Ours is a cultural species, and I believe that our unique attention to sexual choice has helped to mould it.

Most of the world’s literature, most of the world’s art, is preoccupied with the theme of boy meets girl. We tend to think of this as being a sexual preoccupation that needs no explanation. But I think that is a mistake. On the contrary, it expresses the deeper fact that we are uncommonly careful in the choice, not of whom we take to bed, but by whom we are to beget children. Sex was invented as a biological instrument by (say) the green algae. But as an instrument in the ascent of man which is basic to his cultural evolution, it was invented by man himself.

Spiritual and carnal love are inseparable.

 

Chapter 13: The Long Childhood