Mouse to elephant in 24m generations

Published on Tuesday 31 January 2012 00:12

IT TAKES 24 million generations for a mouse-sized animal to evolve to the size of an elephant, scientists have shown.

For the first time researchers have measured how fast large-scale evolution can occur in mammals, and have examined the increases and decreases in mammal size following the extinction of the dinosaurs 65 million years ago.

The team looked at 28 mammal groups, including elephants, primates and whales, from various continents and ocean basins over the past 70 million years.

The findings show changes in whale size occurred at twice the rate of land mammals, thought to be because it is easier to grow big in the water because it supports the weight.

The international team of 20 biologists and palaeontologists also discovered that rates of size decrease are much faster than growth rates. It takes only 100,000 generations for very large decreases, leading to dwarfism, to occur.

Dr Alistair Evans, an evolutionary biologist at Monash University in Melbourne, Australia said the study was unique because most previous work had focused on micro-evolution, the small changes that occur within a species. “Instead we concentrated on large-scale changes in body size. We can now show that it took at least 24 million generations to make the proverbial mouse-to-elephant size change – a massive change, but also a very long time,” Dr Evans said.

“A less dramatic change, such as rabbit-sized to elephant-sized, takes ten million generations.”

The research furthers understanding of conditions that allow certain mammals to thrive and grow bigger and circumstances that slow the pace of increase and potentially contribute to extinction.

Many of the species that have shrunk, such as the dwarf mammoth and dwarf hippo eventually became extinct.

Dr Evans added: “The huge difference in rates for getting smaller and getting bigger is really astounding – we certainly never expected it could happen so fast.”

Dr Jessica Theodor, associate professor of biology at the University of Calgary, and co-author of the study, said: “Our research demonstrates, for the first time, a large-scale history of mammal life in terms of the pace of growth. This is significant because most research focuses on micro-evolution, which are changes that occur within a specific species.”

The research is published in the Proceedings of the National Academy of Sciences USA.

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KINGFISHER1

Tuesday, January 31, 2012 at 03:07 PM

7. I was being polite. I still am. I stick with scientific and technical accuracy of my post. It has nothing to do with Creationism, as currently taught, which like Darwin and Evolution, is also is seriously wrong science. GDR I am a little miffed at 7, but not insulted. It is really a matter for you AMEN. If you do not wish them to understand the Galactic Science at this stage, they can easily be left in the dark. A further 5000 years, perhaps. You can also make 7 understand exactly what I am talking about, and who I am. Locally they are none to hot about HEADS OF GALAXIES! You will have noted the dislike of the GOD figure in the post by 7! The preference is to worship, Darwin or Evolution or a brutal political doctrine. Again as I said previously, my post is as a courtesy. You will appreciate AMEN, that I have withheld the GALAXY name, although the abbreviation is well known, and of course to yourself I have provided much technical detail. The word Delusional is certainly offensive, but perhaps its use simply confirms, in truth, that they have not moved on from Pontius Pilate! And I will not make available to them the video of the scene before Pilate. I despise SHOW TRIALS!!! At issue AMEN, is to let them see the Boats of Milions of Years and to see again the vast populations of our HUGELY ADVANCED SYSTEMS GALAXIES. Your choice, AMEN. It is yours. Stargate the series, is but the fiction. My details MUST have been well checked out, so at issue is the REALITY! This could have been done as RESERVED and REDACTED so that the detail was hidden. I have left reserved the local STAR name,althought that has ben well disclosed by me elsewhere.

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Slioch.

Tuesday, January 31, 2012 at 11:33 AM

#6 MAATT ended, " I post the comment as a courtesy only." ........................................................................................................................ Not courtesy to yourself, that is for sure. Your post is unmitigated delusional nonsense from start to finish. Creationists! Give me a break!

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KINGFISHER1

Tuesday, January 31, 2012 at 11:03 AM

This article is fatuous rubbish. It takes no account of the material factors in the design of the species, nor more particularly the input of the local and the system stars. It showns a very low level of undestanding. Larger animals are only possible with a lower gravity. The worship of Darwin and Evolution, means essentially that the compatability point is not met,unless, of course,the lock down continues to be applied. The extinction process is star contolled. The mammoths and the dinosaurs may be extinct here, but that does not make them extinct even in a Galaxy context,and they can be returned. Species become extinct when the specific constituents parts of the so called dna are returned to source, including to distant Galaxies!!! I post the comment as a courtesy only.

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Slioch.

Tuesday, January 31, 2012 at 09:44 AM

#3 unimpressedone ................. I think you can rest assured that evolutionary biologists in Australia have heard of the Komodo dragon. Both dwarfism (getting smaller) and gigantism (getting larger) of creatures have frequently been recognised on islands (and elsewhere), for what appear to be a variety of reasons. Pointing out one plausible reason for dwarfism on islands does not imply ignorance about gigantism, any more than pointing out that a certain individual in these columns frequently makes asinine comments, does not imply that everyone does.

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Slioch.

Tuesday, January 31, 2012 at 09:31 AM

The first sentence(s) of this article is a little misleading. As I understand it, this is a study of past changes - i.e. of what DID happen under whatever selection pressure existed in past environments. However, if extreme selection pressure was applied to a mouse sized creature - by selective breeding for example - then such size changes would be expected to occur much more rapidly. The first sentence (etc) therefore should have stated, "IT TOOK 24 million generations for a mouse-sized animal to evolve to the size of an elephant, scientists have shown."

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unimpressedone

Tuesday, January 31, 2012 at 09:07 AM

This same study claims that dwarfism in island species is caused by access to limited food supply. Maybe they've never heard of Kodomo dragons?

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antiparasite

Tuesday, January 31, 2012 at 01:37 AM

1,, Or reduce the size, growth.....

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antiparasite

Tuesday, January 31, 2012 at 01:37 AM

The climate, food available and atmosphere would play their part in size also, it would bring around quicker increase in size than breeding would........

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