'Evolutionary leaps' questioned

May 18, 2005
'Evolutionary leaps' questioned

New evidence from fossil fish, hundreds of millions of years old, casts doubt on the latest ideas about evolutionary theory.
The research, by Dr Philip Donoghue of the University of Bristol and Dr Mark Purnell of the University of Leicester, claims to have solved a scientific riddle by using the fossil record to explain evolutionary 'leaps' between species.

The findings will set them on a collision course with geneticists who argue that the evolution of humans and other vertebrates – animals with backbones – was driven by sudden changes in their genes.

This new work challenges the scientific theory that jumps in evolution occurred at times when gene numbers increased in animals with backbones. The larger number of genes is believed to occur through gene ‘duplication’ and is thought to be the reason why humans and other vertebrates are more complex.

When geneticists look at which branches of the vertebrate family tree have duplicated genes and which don’t, it certainly seems that each duplication led to a sudden jump in evolution.

For example, one duplication event occurred sometime after the evolution of lampreys but before the evolution of sharks. Sure enough, lampreys are simple vertebrates lacking jaws, teeth and a bony skeleton, whereas sharks are much more complex animals.

Thus the evidence from living vertebrates suggests a neat pattern, with a close correspondence between gene doubling events and evolution. Indeed, the evidence seems so strong that hundreds of scientific research papers have been written about the genetics of this important evolutionary pattern.

But, as Dr Donoghue explained: “We consider this picture – a view of living animals only – is seriously distorted. What appear to be evolutionary jumps are really just gaps in the evolutionary tree – dead branches that have fallen by the wayside. These branches are not 'missing links', more like ‘missed’ links, and when we use the fossil record to put them back in place, the vertebrate evolutionary tree looks very different."

Dr Purnell said: “The new evidence from research into ancient fossil fish reveals that the 'jump' between lampreys and sharks turns out to be nothing of the sort. The major changes in anatomy didn't occur suddenly, as a result of a gene doubling; they took place over 70 million years or more, through a series of intermediate, but now extinct fossil fish.”

Donoghue and Purnell have thrown down the gauntlet to geneticists, saying: "Fossils may be long extinct, their genes having rotted away millions of years ago, but if geneticists want to say anything meaningful about evolution they must include fossils in the vertebrate family tree – they cannot simply ignore them".

Source: University of Bristol

Explore further: Lunar explorers will walk at higher speeds than thought

add to favorites email to friend print save as pdf

Related Stories

Life on Earth still favours evolution over creationism

Sep 11, 2014

Charles Darwin's Theory of Evolution, first published in 1859, offered a bold new explanation for how animals and plants diversified and still serves as the foundation underpinning all medical and biological ...

Sloths are no slouches when it comes to evolution

Sep 10, 2014

Today's sloths might be known as slow, small animals, but their ancestors developed large body sizes at an amazing rate, according to an evolutionary reconstruction published today in the open access journal ...

New species of titanosaurian dinosaur found in Tanzania

Sep 08, 2014

Ohio University paleontologists have identified a new species of titanosaurian, a member of the large-bodied sauropods that thrived during the final period of the dinosaur age, in Tanzania. Although many ...

Oldest representative of a weird arthropod group

Aug 28, 2014

Biologists at Ludwig-Maximilians-Universitaet (LMU) in Munich have assigned a number of 435-million-year-old fossils to a new genus of predatory arthropods. These animals lived in shallow marine habitats ...

Recommended for you

Miranda: An icy moon deformed by tidal heating

10 hours ago

Miranda, a small, icy moon of Uranus, is one of the most visually striking and enigmatic bodies in the solar system. Despite its relatively small size, Miranda appears to have experienced an episode of intense ...

User comments : 0