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> Super-Predators: Humans Force Rapid Evolution of Animals, Humans are forcing changes in some species 300 percent faster than would occur naturally
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post Jan 13, 2009, 07:17 PM
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Acting as super-predators, humans are forcing changes to body size and reproductive abilities in some species 300 percent faster than would occur naturally, a new study finds.

Hunting and fishing by individual sportsmen as well as large-scale commercial fishing are also outpacing other human influences, such as pollution, in effects on the animal kingdom. The changes are dramatic and may put the survival of some species in question.

In a review of 34 studies that tracked 29 species across 40 different geographic systems, harvested and hunted populations are on average 20 percent smaller in body size than previous generations, and the age at which they first reproduce is on average 25 percent earlier.

"Harvested organisms are the fastest-changing organisms of their kind in the wild, likely because we take such high proportions of a population and target the largest," said lead researcher Chris Darimont of the University of California, Santa Cruz. "It's an ideal recipe for rapid trait change."

Darimont told LiveScience that while he considers the changes to be evolutionary, some biologists consider them phenotypic and, without evidence of genetic shifts, would not call them evolution.

The study found dramatic change in several fish species and creatures as small as snails and as large as bighorn sheep and caribou.

Dominant force

The results, published online today in the journal Proceedings of the National Academy of Sciences, are similar to a host of other scientific conclusions dating back nearly two decades.

In 1990, Douglas Chadwick wrote in National Geographic magazine how trophy hunting — the practice of selecting only the largest beasts to kill —"has caused a decline in the average size of Kodiak Bears [in Alaska] over the years."

By harvesting vast numbers and targeting large, reproductively mature individuals, human predation is quickly reshaping wild populations, leaving smaller individuals to reproduce at ever-earlier ages, Darimont explained.

"The pace of changes we're seeing supercedes by a long shot what we've observed in natural systems, and even in systems that have been rapidly modified by humans in other ways," Darimont said. The study found the changes outpace by 50 percent those brought on by pollution and human introduction of alien species.

"As predators, humans are a dominant evolutionary force, he said.

Others agree the problem is serious. Columbia University biologist Don Melnick recently said trophy hunting is akin to selective breeding and is "highly likely to result in the end of a species."

Surprising ability to change

One surprise: The capacity of creatures to change.

"These changes occur well within our lifetimes," Darimont said. "Commercial hunting and fishing has awoken the latent ability of organisms to change rapidly."

Changes occur in two ways. One is sheer genetics:

Evolution can favor smaller fish able to pass through the mesh of gill nets and survive to reproduce, thereby passing on genes for smaller offspring.

Another change process is called plasticity. Shifts to earlier reproduction, for example, can occur because there is a lot of food and fewer fish to dine on it. The fish eat more and reach maturity sooner.

"Whatever the underlying process, shifts to earlier breeding spell trouble for populations," Darimont said. "Earlier breeders often produce far fewer offspring. If we take so much and reduce their ability to reproduce successfully, we reduce their resilience and ability to recover."

One specific example: the overfished Atlantic cod on the eastern coast of Canada. Less than two decades ago, they began mating at age 6. Now they start at age 5.

Government problem

In some cases, as other studies have found, the problem results from decades of big-game hunting and, more recently, poaching. Some populations of African elephants, for example, have unnatural percentages of tusk-free animals among them now, because hunters and poachers favor the ivory.

But some government rules contribute to the problem.

"Fishing regulations often prescribe the taking of larger fish, and the same often applies to hunting regulations," Darimont said. "Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we're seeing the consequences of this management."

Darimont thinks new policies are in order.

"While wolves might prey on 20 animals, humans prey on hundreds of thousands of species," he points out. "We should be mimicking natural predators, which take far less and target smaller individuals."

Policy shifts may or may not save a species, however.

"It's unknown how quickly the traits can change back, or if they will," Darimont said
Robert Roy Britt

http://www.livescience.com/animals/090112-...-predators.html
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trojan_libido
post Jan 14, 2009, 03:53 AM
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I had this brought to my attention by an article called 'Incredible Shrinking Fish...'

I was not surprised to here that evolutionary pressures could change a creature much much faster than hundreds of generations which is the view that the average person (e.g. me!) gets from Darwinian evolution.

I think the process of evolution should not be restricted to evolution within species. The Universe has always been evolving, life appearing was a continuation of that process and in no ways seperate. Behaviours, societies, cultures, speech and everything beyond the singular biological organism has also evolved.

Some examples of processes I feel are real-time evolutions:

Muscle growth - do weight lifting with only one arm and see it happen. This is our body automatically evolving to what it perceives as an environmental pressure.

Bone strength increasing - by stressing our bones over and over, increased bone strength will result. A documentary called 'Superhuman' in the UK showed huge weight lifters and other martial artists showing the results of their hard work. They showed the average strength of a persons bone was 10 (made up number), after this it would break. Then they brought two guys on who'd made it their mission in life to be stunt men. They'd routinely thrown themselves off buildings, smash bricks with their bare arms and other crazy macho things. They attached a sensor to these guys arms to see how fast the deceleration of their impact was, and they could extrapolate the 'pounds per square inch of pressure' (or similar). They were expecting a reading that was below the threshold point of a broken arm, but the actual result was 40-45 (again made up, but proportions are correct). They showed how by stressing the arm over and over, the two stuntmens bodies had actually evolved supporting struts between the marrow and massively increased the bone strength. Again this is the body evolving to suit the environment, and in one persons lifetime.

Sensory adaptations - people with less stimuli than average (blind, deaf) have improved sensory abilities in the other areas. Whether this is due to less of the brain being used and therefore more is used for the other senses, or whether its because of the environmental pressures of being disabled in some fashion is a question thats neither here nor there.

Other places where I feel evolution occurs in real time are below:

Driving - new drivers are very heavy footed, they've not required to have a foot capable of minute movements to get a smooth gas pedal movement. The body automatically (through practice, and little else) develops the ability to sense and respond at the level required.

Surgeons - they develop their fine motor skills, other than heriditary illnesses like Parkinsons, a super steady hand and accurate eye is not something you're born with.

Babies continue to evolve into whatever environment they're in. Language skills, cultural traditions, fashion and moralities are all copied from the environmental pressures of parents and peers.

Ideas evolve, Language evolves (txt speak, acronymns, new words or altered meanings).

Art - learning to use a fine tool like a pencil has the same issues as the heavy footed learner driver. Musical instruments like piano and guitar require practice to gain the motor skills and co-ordination required. Musical theory is studied, but the link between the instrument and whats in the musicians head is entirely automated. The links in the brain have evolved from the environmental pressure of the musician sitting at his instrument for so long. The level of fine motor skills and co-ordination required are extraordinary, and with the exception of savants, not a single person is born with the ability. I don't believe its simply practice makes perfect, I believe its our body fine tuning its capabilities to what the requirements are, in the same way as the other examples above.

If Practice = Perfect, and practice is a form of real-time evolving from environmental pressures, then is the point of evolution to seek perfection (ie efficiency) in whatever environment the organism is in?

If the Universe is simple and gathered complexity as it went (stars forming more complex elements), and we've identified evolution as the biological method of transformation, its not a great leap to evaluate everything after the biology as an evolution too. Evolution is probably the ONLY process, it simply appears different depending on where its found.


Many spiritual ideas are based around the fact that living is Being, and that the Universe is in a constant state of transformation. The stoy of the Ugly Duckling, the caterpillar transforming into a butterfly.

My point is: Evolution is not restricted to biology! Everthing is in a constant state of transformation, and from these transformations comes evolution.
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post Jan 14, 2009, 05:13 AM
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QUOTE(trojan_libido @ Jan 14, 2009, 03:53 AM) *


My point is: Evolution is not restricted to biology! Everthing is in a constant state of transformation, and from these transformations comes evolution.

Good point. But this kind of human-driven evolution of the species shouldn't be called evolution, as the writter points out. I say we should call it Devolution!
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trojan_libido
post Jan 14, 2009, 05:25 AM
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The term 'Evolution' is restricted to biology at present, I believe the same process was present before and after biologically sentient beings evolved to top dog. I guess I'm calling for a change in the term Evolution, or the recognition that evolution continues outside of biology.
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thefield
post Dec 18, 2009, 09:54 PM
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do we really have any evidence that species are evolving on such a short timeframe? genetic change, at least from my understanding, happens on a much longer period.
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post Dec 19, 2009, 12:19 PM
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QUOTE(thefield @ Dec 19, 2009, 05:54 AM) *

do we really have any evidence that species are evolving on such a short timeframe? genetic change, at least from my understanding, happens on a much longer period.
Most organisms evolve very rapidly. The idea of the opposite is fallacious. This is probably due to the view of evolutuion by most people as change in fossil evidence of past species, where for example the limited number of fossils for some organisms (eg T rex) implies that change is over millions of years or longer. I can easily justify my statement through the idea of the number of mutations that occur in the genome of any organisms per short time period (eg day) due to radiation, chemicals etc in/from the environment. Think of antibiotic resistant bacteria for an example of rapid evolutionary change.
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