Sunday, January 21, 2007

Human genetic experiments take an odd twist

By the time a story hits the front page of CNN's Web site, it's probably been digested many times over in smaller journalistic circles. And having seen what national/international media can do to the facts of various industries, I take whatever I read there with a huge grain of salt.

Still, it's curious to find that some people with genetic variations may want to propagate them through selective embryo screening.

Now, if blond-haired, blue-eyed people wearing Swastikas (btw -- did you know that most Nazis did not have blond hair?) were to put together a breeding program to create super-human beings or some such nonsense (which has been written about in science fiction for years), nearly everyone on the planet would be up in arms, looking for the secret laboratories. We don't need no stinkin' racist supermen.

But the CNN story looks at the angle from the other direction. Will people be as incensed and offended when they realize that couples with physical disadvantages -- such as dwarfism -- may want to have children who share the same disadvantages with them?

Every time I see an article about ancient human populations or modern human genetic control ethics, I wonder how it is that we have come to be who we are through what science calls "the evolutionary process". Now, before you start branding me a "genetic interventionist" or whatever, understand that I'm only looking at the scientific side of the issues.

For decades, scientists have struggled to explain how we became human. They have proposed speciation events must have occurred, where small, isolated populations of early hominids were cut off from other hominids for long periods of time (hundreds of thousands of years). For whatever reasons, one group of hominids surpassed all others during each speciation phase.

So one group of Australopithecines (the hobbit-sized "Lucy" who lived 3,000,000 years ago was an Australopithecine) was cut off from all others and this one group evolved into the early Homo Sapiens ancestors many scientists have called Homo Erectus or Homo Ergaster. The Erectus/Ergaster groups became divided across three broad regions: some remained in Africa, some went north to Europe, and some went east to Asia.

The Neanderthals are believed to have evolved from Homo Heidelbergensis families (descendants of African Homo Ergasters) who spread north in a later migration. But there remains the question of whether Neanderthals and Modern Humans intermingled. Two interspeciation points have been proposed (that I am aware of): the Middle East and western Europe.

In East Asia, the descendants of Homo Erectus supposedly lasted about 1,000,000 years before dying out. They were ultimately replaced by Modern Humans.

Modern Humans are believed to have evolved in Africa (which means that all blond-haired, blue-eyed people are descended from dark-skinned people -- so much for the "pure Nordic race"). Every few tens of thousands of years, new waves genetically more advanced people swarmed out from Africa to expand into other regions of the world.

The statistical implication is that the human evolutionary process occurs fastest in small, isolated populations that must adapt to radical changes in environment. If a population can expand into wider and wider territory, there is no evolutionary impetus for advantageous genes to cluster together and produce a "leap forward" (as the voiceovers in the "X-Men" movies indicate).

So where does that leave modern humanity? Science fiction writers have often suggested or argued that a population which achieves a state of civilizaion stops evolving. Recent genetic evidence suggests that is not so. In fact, as recently as a few thousand years ago we acquired the ability to digest milk in adulthood (a genetic trait which is still not found in some parts of the world).

Recent research suggests that humanity's most recent common ancestor lived about 60,000 years ago. Some people are already suggesting that genetic mutations occur at a much faster pace in human experience than previously believed.

But in order for a new species to appear, more than one genetic mutation must become fixed (dominant) in a population. Despite a wide array of genetic variations in modern humans, we are still the same species. The question of whether we can spin off a new species in a world of highly interconnected sub-groups is both scientifically intriguing and ethically confusing.

The process would have to begin with intentional human genetic breeding. That is, even something as relatively simple as prescreening embryos constitutes a breeding process, in the sense that we are selecting offspring for a specific outcome. We breed dogs, cats, horses, cattle, and many other animals. Have we now come down to breeding ourselves?

And if we achieve the ability to create a species on demand, should we use it?

3 Comments:

Anonymous Patrick Slavenburg said...

There is in fact evidence that genetic changes can occur within 1 or 2 generations. I cannot remember all the facts (nor would this be the venue to extensively describe them) but there was a study in the early 2000's in Sweden where a correlation was found between early deaths (i.e. not reaching the 75-80 year old age) and the fact their grandparents had been in a hunger period in the 1930's while being pregnant of one of their parents.

Similarly there seems to be a strong indication (but in my opinion as with much medical research the groups often are too small for great statistics) that women over 6 months pregnant and having a post traumatic stress disorder after sept. 11 have actually "transferred" some aspects of that disorder to their foetus and later the child.

There are more examples. Still doesn't change a species but it IS quite interesting that it's not only the genes that count but to which extend one can switch on/off these genes or parts of genes from one generation to another. In other words.. smoking, stress etc.. could have a permanent impact on your children if in the "right" month of pregnancy or the "right" time of the creation of semen in men.

6:32 PM  
Blogger Michael Martinez said...

I have read some papars/articles that argue genetic alteration can indeed occur within the womb. That is, in one experiment, a patch of brown fur was grafted onto a white furred lab rat and the rat's babies were born with a mixture of brown and white fur.

The whole question of "how did we turn on our ability to ingest milk as adults" really implies something like that. After all, why would the gene become dominant if we were not already trying to drink milk as adults?

Some people must have suffered hard days and nights, perhaps during a famine, trying to survive, and they forced their bodies to ingest milk. The unborn babies may have picked up the need to continue this ability into adulthood.

I think human change has been faster than previously believed, and it may actually have happened faster because of choices our ancestors made, much less than through unaware "natural selection" (which doesn't take into account the effects of natural disasters).

7:17 PM  
Anonymous Patrick said...

I totally agree. Another nice example is alcohol. During the black plague, people could not just drink normal water. Instead they chose all sorts of fermentation processes.. hence the drinking of beer and wine (and yes they drinks are older than that ofcourse, even before the Greeks), but this was in quite a massive scale (simple protection). In Asia people used to boil their water and drink e.g. tea. Hence the ability of the Europeans to drink alcohol and the sensitivity of many people in Asia against it.

I hope I phrased this well, but OK, you get the idea.. it actually comes very close to the drinking milk story.

Patrick

2:56 AM  

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