October 20 12, p. 26). It is the first small step on the road towards a daring goal: the copying of a human brain into another material – for instance, the silicon of computers.
14 Edward O. Wilson,
Consilience
.
15 Sharon Begley, ‘In Our Messy, Reptilian Brains’.
16 Spike Feresten, ‘The Reverse Peephole’,
Seinfeld
season 9 episode 12, 15 January 1998.
17 An outgrowth of a support cell known as a glial cell sheaths some neurons. The myelin sheath stops the electrical current of the axon leaking out into the surroundings just as plastic insulation stops electricity leaking out of the wires in your home. This is important if the current has to travel a long way – for instance, down the spine to the muscles of a limb. Myelin is white so neurons encased in itare called white matter in contrast to the grey matter of the rest of the brain. People with multiple sclerosis, or MS, progressively lose the myelin sheaths around their white matter and so gradually lose the use of their limbs. Their thought processes, which are carried out in the grey matter, however, remain unaffected.
18 Gerald D. Fischbach, ‘Mind and Brain’,
Scientific American
, vol. 267 no. 3 (September 1992), p. 49.
19 Tim Berners-Lee,
Weaving the Web: The Past, Present and Future of the World Wide Web by its Inventor.
20 Doris Lessing,
The Four-Gated City.
21 George Johnson,
In the Palaces of Memory: How We Build the Worlds Inside Our Heads.
22 Marvin Minsky,
The Society of Mind.
23 James Watson,
Discovering the Brain.
24 George E. Pugh (son of Emerson Pugh),
The Biological Origin of Human Values.
6:
THE BILLION PER CENT ADVANTAGE
Human Evolution
Man still bears in his bodily frame the indelible stamp of his lowly origin.
CHARLES DARWIN ,
The Descent of Man
We are just an advanced breed of monkeys on a minor planet of a very average star.
STEPHEN HAWKING ,
Der Spiegel
, 17 October 1988
Once upon a time, there was a primitive species of forest-dwelling ape. For some reason it split into two separate populations. Perhaps it became divided by a mountain range or a treeless corridor; nobody really knows the truth. However, because the two populations became subject to different survival pressures, they diverged and turned into two distinct species. One species was destined to lead to chimpanzees, the other to human beings.
The precise date of the fork in the road between the ancestors of humans and our closest living relatives is not known. But the best bet is that it happened between about 6 and 7 million years ago. This is so recent in evolutionary terms that it explains why we share an astonishing 98–99 per cent of our DNA with chimpanzees. Strikingly, however, chimpanzees do not use language, build cities, program computers or fly to the Moon. Somehow, the 1–2 per cent genetic difference has been amplified into a billion per cent advantage in the real world.
Understanding how such a minuscule difference in DNA can make such a big difference in practice involves understanding a subtlety of DNA. The popular picture is of a molecule that encodes a series of instructions, or genes, for the building of proteins that determine everything from eye colour to blood group. But there is more to DNA than this. Some genes have the ability to switch on and switch off other genes, controlling the order in which they are read out, or expressed, in a developing embryo.Although such regulatory genes account for only a small fraction of the 1–2 per cent difference between the DNA of humans and chimpanzees, crucially they have a dominant effect on the process of development. 1
Think of regulatory genes as the recipe and standard genes as the ingredients. Similar ingredients, when combined according to different recipes, can create very different dishes. Take eggs. Depending on how they are cooked (or not), it is possible to end up with raw eggs, soft-boiled eggs, hard-boiled eggs, pickled eggs, poached eggs, fried eggs, scrambled eggs, an
14 Edward O. Wilson,
Consilience
.
15 Sharon Begley, ‘In Our Messy, Reptilian Brains’.
16 Spike Feresten, ‘The Reverse Peephole’,
Seinfeld
season 9 episode 12, 15 January 1998.
17 An outgrowth of a support cell known as a glial cell sheaths some neurons. The myelin sheath stops the electrical current of the axon leaking out into the surroundings just as plastic insulation stops electricity leaking out of the wires in your home. This is important if the current has to travel a long way – for instance, down the spine to the muscles of a limb. Myelin is white so neurons encased in itare called white matter in contrast to the grey matter of the rest of the brain. People with multiple sclerosis, or MS, progressively lose the myelin sheaths around their white matter and so gradually lose the use of their limbs. Their thought processes, which are carried out in the grey matter, however, remain unaffected.
18 Gerald D. Fischbach, ‘Mind and Brain’,
Scientific American
, vol. 267 no. 3 (September 1992), p. 49.
19 Tim Berners-Lee,
Weaving the Web: The Past, Present and Future of the World Wide Web by its Inventor.
20 Doris Lessing,
The Four-Gated City.
21 George Johnson,
In the Palaces of Memory: How We Build the Worlds Inside Our Heads.
22 Marvin Minsky,
The Society of Mind.
23 James Watson,
Discovering the Brain.
24 George E. Pugh (son of Emerson Pugh),
The Biological Origin of Human Values.
6:
THE BILLION PER CENT ADVANTAGE
Human Evolution
Man still bears in his bodily frame the indelible stamp of his lowly origin.
CHARLES DARWIN ,
The Descent of Man
We are just an advanced breed of monkeys on a minor planet of a very average star.
STEPHEN HAWKING ,
Der Spiegel
, 17 October 1988
Once upon a time, there was a primitive species of forest-dwelling ape. For some reason it split into two separate populations. Perhaps it became divided by a mountain range or a treeless corridor; nobody really knows the truth. However, because the two populations became subject to different survival pressures, they diverged and turned into two distinct species. One species was destined to lead to chimpanzees, the other to human beings.
The precise date of the fork in the road between the ancestors of humans and our closest living relatives is not known. But the best bet is that it happened between about 6 and 7 million years ago. This is so recent in evolutionary terms that it explains why we share an astonishing 98–99 per cent of our DNA with chimpanzees. Strikingly, however, chimpanzees do not use language, build cities, program computers or fly to the Moon. Somehow, the 1–2 per cent genetic difference has been amplified into a billion per cent advantage in the real world.
Understanding how such a minuscule difference in DNA can make such a big difference in practice involves understanding a subtlety of DNA. The popular picture is of a molecule that encodes a series of instructions, or genes, for the building of proteins that determine everything from eye colour to blood group. But there is more to DNA than this. Some genes have the ability to switch on and switch off other genes, controlling the order in which they are read out, or expressed, in a developing embryo.Although such regulatory genes account for only a small fraction of the 1–2 per cent difference between the DNA of humans and chimpanzees, crucially they have a dominant effect on the process of development. 1
Think of regulatory genes as the recipe and standard genes as the ingredients. Similar ingredients, when combined according to different recipes, can create very different dishes. Take eggs. Depending on how they are cooked (or not), it is possible to end up with raw eggs, soft-boiled eggs, hard-boiled eggs, pickled eggs, poached eggs, fried eggs, scrambled eggs, an
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