Human evolution and skin colour – the dreadful truth!

Posted on by Opher

DSCF1546

Human evolution and skin colour.

As we migrated out of Africa a mere sixty thousand years ago we hit a problem. The sunshine and hence UV light was greatly reduced. We needed that UV light in order to make Vitamin D. Without vitamin D we got ill. When you are living on the edge any small advantage becomes crucial.

In strong UV Light the black pigment melanin provides protection against skin cancer.

We all stem from Africans who had black skin.

Outside of Africa black skin was a disadvantage. A mutation occurred that reduced melanin and resulted in lighter skin that upped our vitamin D production.

Pale skin was selected in subtropical regions.

It is interesting to observe the way natural selection has occurred to optimise protection against skin cancer and vitamin D production. I tropical regions with harsh UV the skin colour is black. In subtropical regions with less intense UV it is brown and in temporate regions it is very pale.

This is a good example of changes in the ratio of genes in a population and hence evolution.

Humans and why we’re not evolving.

Posted on by Opher

DSCF1549

Humans and why we’re not evolving.

It is unlikely that we are evolving much at present. We have removed most of the selection pressures that cause evolution. Our amazing brains have produced science and technology that have removed much of the Natural Selection that operated on our populations in the past – at least in the developed countries and increasingly in the undeveloped ones.

We have:

  • Killed off predators
  • Conquered most diseases that would previously have killed us off before we had a chance to breed
  • We have improved sanitation and clean water
  • We have gained a secure food supply.All that is killing us off early is war, accidents and selfish greed.However there is some evolution. The fact that some people choose not to have children while others have many will, in time, skew the numbers of genes in the population. Is it a worry that it is the least intelligent and least educated that are reproducing most? Probably in the long term, if it is a trend that continues. Education is probably the answer to that one.Overpopulation will lead to war, food shortage and disease. Probably a new virus will emerge to which we have no resistance. Only those with a mutation that provides immunity will survive – or maybe nobody.The only difference between all of them and us is that we will be the first to do it to ourselves through our own greed, arrogance and foolishness. So much for intelligence. Without other qualities it counts for little.Time will tell.
  • So will we evolve? Be a blip? A tiny layer in the strata of time?
  • Science has demonstrated that 99.9% of all animals that have evolved have passed into extinction.
  • But this state of affairs is a blip. It will not last. Soon the selection pressures will return with a vengeance. Our numbers have grown out of proportion and our intelligence will not outdo the threats.
  • 95% of us survive long enough to have children.

Evolution within Humans.

Posted on by Opher

DSCF1548

Evolution within Humans.

Up until recently in was easy to see evolution at work on human populations through natural selection. In Shakespeare’s day, four hundred years ago, only one in three babies survived long enough to reproduce. There was a huge mortality rate. The ‘unfit’ were weeded out through disease, bad conditions, lack of sanitation, malnutrition, violence or mere bad luck. To survive you needed the right genes and the wit to be in the right place and do the right thing.

Nowadays 95% survive. The ‘unfit’ (and I use that term scientifically, not unkindly) are not weeded out. Health and Safety, medicine, sanitation and cleanliness have created a situation where nearly everyone survives to have children.

So is evolution no longer occurring in human populations?

The answer is probably ‘not much’.

Wonder and Awe – Human Evolution.

Posted on by Opher

evolution evolution6

We were not always alone as we are now. Although we share 99% of our genes with chimpanzees and gorillas, our closest living relatives, we are different. The prime difference being the size of our brains and our intelligence. Once there were a whole host of different humans.

We evolved in the Rift Valley in Ethiopia. We are all of African descent. We are all one species.

The fossil and DNA evidence is conclusive. Racists and creationists have nowhere to hide. All they can do is deny.

A mere five million years ago our common ancestor split off from the chimp line. The Australopithecines had a brain weight of 500 grams (slightly bigger than a chimp). By 1.8 million years ago there were numerous groups of hominids living in the Rift Valley region. We were not alone. They included Homo habilis and Homo erectus.

Life in the Rift Valley was precarious. There was a lot of climatic change.

By 1.4 million years ago only Homo erectus had survived. But their brain size had evolved to 1000 grams.

800,000 years ago Homo heidelbergensis had evolved. Their brain weight had jumped to 1400 grams (comparable to modern man). They gave rise to both the Neanderthals and Homo sapiens.

Homo sapiens evolved with a brain weight of 1500 grams only 200,000 years ago. We lived alongside our close, and more intelligent, cousins Homo Neanderthal until 45,000 years ago.

We have only been alone for 45,000 years. What a mess we’ve made of things in such a short time!

We are so new that if you took a baby from 200,000 years ago and brought them up in the present day they could be a nuclear scientist, president or rocket scientist without any trouble. We haven’t changed. Our brains are the same.

I like to imagine that somewhere, in a secluded garden of Eden, hidden away, a group of surviving Neanderthals have set up home. Despairing of the destructive violence of their cousins they cloistered themselves away.

I wonder what they would make of the world we have made and our invention of war, religion, pollution, overpopulation, politics, climate change, cruel ways to kill other animals and enough greed, selfishness and power-madness to destroy the planet.

Perhaps with their wisdom and intelligence they could convince us that there is a better way of living. We could take a lesson from the whales and dolphins. We could be gentle and live in a self-sustaining manner in harmony with each other and the planet.

I hope we find them soon. I’m scared of being alone with the megalomaniacs raging around me.