Human evolution slower than thought

2011-06-13 07:28
Paris - Humans may be evolving a third as slowly as commonly thought, according to an investigation into genetic changes in two generations of families.

The genetic code comprises six billion nucleotides, or building blocks of DNA, half of which come from each parent.

Until now, the conventional theory among scientists was that parents each contribute between 100 and 200 changes in these nucleotides.

But the new study says that far fewer changes occur. Each parent hands on 30 on average.

"In principle, evolution is happening a third as slowly as previous thought," said Philip Awadalla of the University of Montreal, who led the study by the CARTaGENE group.

New ground

The discovery came from a painstaking look at the genomes of two families, each comprising a mother, a father and their child.

The study breaks new ground although its sample size is very small.

If confirmed on a wider scale, it will have a bearing on the chronology of evolution. It would change the way we calculate the number of generations that separate Homo sapiens from a primate forebear who is also the ancestor of the apes.

The study also challenged thinking about whether DNA changes are more likely to be handed on by the father or by the mother.

The mainstream notion is that DNA changes - known in scientific terms as mutations - are likelier to be transmitted by the man.

This is because mutations occur during cell division and DNA replication, and thus are much likelier to happen in sperm, for which many millions are made, than in eggs.

In one of the families, 92% of the changes were derived from the father.

But in the other family, only 36% of the mutations came from the paternal side.

"The mutation rate is extremely variable from individual to individual or... some people have mechanisms that reduce the likelihood of mutations," concluded Awadalla.

This variability could prompt a rethink on predicting the risk of inherited disease, caused by flawed genes bequeathed by one or both parents.

Some individuals might be at risk of misdiagnosis of a genetic disease if they have a higher natural mutation rate than the benchmark rate, he suggested.
Read more on:    research

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

linking and moving

2015-04-22 07:36 publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24


Miley Cyrus can’t get enough of her new puppy

Miley's new dog is too adorable.



13 guilty pets
Meet SA's top poacher-catcher
The unusual pets of Instagram
Bertie sets a new world record!

Book flights

Compare, Book, Fly


Plant some seeds. Your innovative mind is on fire and your ingenious ideas may just be the seeds for future projects. You may more

There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.