Peter Forbes

The story of the hour is the prospect of curing mitochondrial diseases by implanting a third person’s mitochondrial genes in an egg during IVF. It’s controversial because it raises the spectre of human genetic engineering and would require new legislation to legalise it. But a bit of background will help us here.

Mitochondria are the cell’s batteries, little structures inside every cell that provide our energy. They have a most curious property in that they have their own DNA, separate from the rest of our DNA, that is only inherited from the mother. The other oddity about the mitochondrion is its genesis. It is now virtually certain that mitochondria were once free living single celled creatures. Life in those days – we’re talking of around 2 billion years ago – consisted only of single-celled creatures: life was a matter of one cell engulfing another and digesting it: the war of the cells. It wasn’t a pretty world, by our standards, and this went on for about 1 billion years before multicellular organism began to evolve. But sometimes, instead of one cell consuming another, both cells found an accommodation: one continued to live inside another and both benefited: symbiosis. This also happened in the line that led to plants: the green of plants comes from the photosynthetic chloroplasts, also once free-living organisms.

Over time, many of the genes in the mitochondria have been lost or been incorporated into the host genome – only 37 remain. But the mitochondria are vital – if they seriously malfunction, life is not possible.

So when genetic modification of mitochondria is proposed what we are really talking about is not human genetic modification but a form of bacterial modification: the bacterium just happens to be part of us. We don’t scruple to tinker with our most basic bits of plumbing. If the heart is failing we implant a pacemeaker. This is not considered to be dehumanizing. But tinkering with our genes is thought by some to transgress human integrity. This is illogical. The team in question is at Newcastle University and the head, Professor Doug Turnbull, put it succinctly: "What we've done is like changing the battery on a laptop: the energy supply now works properly, but none of the information on the hard drive has been changed”.

Jonathan Latham's Guardian article today suggests that genes are mostly NOT responsible for diseases. He cites the relative failure of the Human Genome Project, now in its 10th year since partial completion, to produce medical benefits.

This attitude is highly irresponsible, feeding a fear of things genetic (as in GM food) that is second only to thing nuclear. People forget, or never knew, that genes don’t simply set you going as a human, with your parental inheritance etc. They are active all the time in every cell making the chemicals the body needs to function normally. In a healthy person, only a limited number of the 25,000 or so genes are active in any one type of cell. That way they can make just the chemicals needed to metabolize sugars, or create the light-sensing pigments of the eye, or grow nails or protect against infections. If a gene gets out of control a body function may be compromised or cancer may result.

As far as the human genome project goes, it is well known that a limited number of serious diseases are caused by a single gene errors (so-called snips – single nucleotide polymorphisms). Some of these are :Huntington's disease, neurofibromatosis type 1, Marfan syndrome, cystic fibrosis, sickle-cell disease, Tay-Sachs disease,  Hemophilia A, Duchenne muscular dystrophy, and Lesch-Nyhan syndrome as well as common and less serious conditions such as male pattern baldness and red-green color blindness. These are the low hanging fruit

Many other serious diseases – such as diabetes, heart diseases – Alzheimer’s, are multi-gene diseases and much harder to understand. Of course many conditions are caused by infective organisms or environmental toxins but these all still have to interact with the body’s genetic mechanisms. You can’t study these without taking the gene cascades into account.

I fear that Latham’s article will encourage the obscurantist tendency and greatly hinder medical research.

What did it feel like to win the Warwick Prize? I feel I have to borrow Joyce Cary’s words from The Horse’s Mouth: “A rapid glow, resembling a measles rash, broke out all over my body. And I said to myself. This is not only fame it is self-satisfaction. I shall now be able to leave off my winter vest, at least for the summer”.

I first became interested in mimicry over 25 years ago when I was editing natural history encyclopaedias. The most interesting creatures seemed to be those that were trying to be something else – butterflies like leaves, plants like stones, alligators with little wriggly worms as a lure inside their gaping mouths. I started to see mimicry everywhere and developed the theory that the sperm whale’s impossibly slender lower jaw was a mimic of the tentacles of the giant squid it fed on. The squid were lured by this appendage and were no match for the leviathan.

I published the article in New Scientist and Heathcoat Williams later republished it in his book Whale Nation. The cetologists have kept mum on the subject to this day. In that Horse Mouth mood after the prize, I was idly googling when the sperm whale jaw article popped up, in facsimile. New Scientist’s archive has been digitized and is available, free, online in this evocative form, ,mimic the print issue. I was able to read again all my early efforts which eventually led to Dazzled and Deceived. That’s self satisfaction – even if it did take two and half decades.

Christopher Lloyd is a historian for the big picture, believing that history should now include our relationship with the natural and material worlds. Now, he's followed his large illustrated books What on Earth Happened? and What on Earth Evolved? with a Wallbook that opens out to tell the human story from the Big Bang to now. Cunningly arranged, with more information than you'd think possible in such a span, it's a great way of taking your bearings on how we got to this point. The text on the reverse of the chart also does a brilliant job of topic selection. It is particularly good on the emergence of our culture, picking up techniques along the way, especially domesticating crops and animals. The What on Earth? Wallbook is currently available at £15 from the What on Earth? website or call 01443 828811.