The Hindu Business Line : DNA isn't destiny, it's history

Life is a complicated gift, "an impossible assemblage of biology, chemistry, electricity, and engineering," and disease is part of the package, argues Dr Sharon Moalem in Survival of the Sickest (www.landmarkonthenet.com) .

"Our relationship with disease is often much more complex than we may have previously realised." So, ask the whys, encourages the author. Pose questions, such as: "Why does malaria want us in bed but the common cold want us at work? Why do we have so much DNA that doesn't seem to do anything? Why do the great majority of people with type 1 diabetes come from Northern Europe?"

And, why do humans have less hair than animals? Curious phenomenon, one learns, because "every hairless mammal is aquatic or at least plays in the mud - think of hippos, elephants, and the African warthog. But there aren't any hairless primates."

Moalem cites elaborate research including that of Elaine Morgan who came up with `the aquatic ape hypothesis': that our pre-human ancestors spent a long time in and around the water.

"They caught fish and learned to hold their breath for long periods while diving for food." The theory explains how like many other aquatic mammals, we lost our fur, says the author. "It explained the development of our prominent nose with the downward-facing nostrils, which allowed us to dive."

Another ageless question is, "Why do we age?" Ageing confers an evolutionary benefit on the species, if not on the individual, says Moalem. "Ageing acts like a biological version of planned obsolescence... It makes the way for new, improved versions." Also, "Ageing can protect the group by eliminating individuals that have become laden with parasites, preventing them from infecting the next generation."

He compares this to Apple's iPods, manufactured with "batteries that only lasted about 18 months and couldn't be replaced." Faced with criticism that the company was "forcing consumers to buy a new model when their battery died," Apple has a battery replacement programme, or more exactly an iPod replacement programme — "for a small fee, they send you a new or refurbished equivalent to your now-powerless purchase."

Writing about cancer, `a family of diseases characterised by cell growth gone haywire,' Moalem reassures that the body has multiple lines of cancer defence.

"There are specific genes responsible for tumour suppression. There are genes responsible for creating specialised cancer hunters programmed to seek and destroy cancer cells. There are genes responsible for repairing the genes that fight cancer."

If that's amazing, there's more. Cells have a mechanism to commit a kind of hara-kiri! "Apoptosis, or programmed cell death, occurs when a cell detects that it has become infected or damaged - or when other cells detect a problem, and `convince' the dangerous cell to kill itself... "

DNA isn't destiny, it's history, observes Moalem. "Somewhere in your genetic code is the tale of every plague, every predator, every parasite, and every planetary upheaval your ancestors managed to survive. And every mutation, every change, that helped them better adapt to their circumstances is written there."

In a universe that is geared toward chaos and disorder, it is a wonder that we live at all, concludes the book. "Which is why, instead of taking our health for granted, we should appreciate it with the reverence it deserves."

Prescribed read.

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