It has become increasingly common to hear reports that big brains are not necessary, or even an evolutionary fluke. However, the new article found that increases in the size of brain areas, such as the visual cortex, are an essential element of evolution.
As part of the study, the...
Anonymous asked:
theoriginofthespecies answered:
My favorite misconception about evolution.
If you are going to deny the fact of evolution you need to understand how evolution actually works first.
The quick answer is that humans didn’t actually evolve from monkeys. But we did both evolve from a common ancestor who happened to look more like an ape than a human.
So where did the ape-like ancestor go? Why did this ancestor evolve into humans and modern apes?
This is where evolution comes in. Evolution is a natural process that changes all living things over many generations.
Evolution requires at least two things. First, we all have differences in our DNA, the instructions for making every living creature. These DNA differences lead to various eye colors, skin colors, blood types, and all of the other variation that exists between each of us.
Some of these DNA differences don’t matter. Others can be bad and cause diseases and even death. And some of these differences in DNA can help a person to live longer or stay healthier. For example, one DNA difference seems to make people more resistant to HIV and maybe also smallpox and the plague.
Second, evolution requires that DNA be passed from one generation to the next. This way, any survival advantage can be passed from parent to child.
Combining these, evolution works because animals (or other living things) with beneficial DNA differences usually survive longer and are able to have more kids. And those with bad DNA changes often die before they can have kids. Over time, more and more animals have the good DNA, and fewer have the bad DNA. This is called natural selection.
So now that we understand evolution and natural selection, how can this explain why we have humans and apes?
One way natural selection can work to evolve new species is if the old species gets split into two groups. The two groups have to be separated in different environments for a long time. This is what might have happened to cause modern apes and humans to appear. The story probably went something like this.
Sometime between eight million and five million years ago, Africa had more rain and was covered by forests. During this time, an ape-like species (our common ancestor) lived in these forests. They were quite successful and spread all over the continent.
Then the climate began to change, the land began to dry out, and the forests began to disappear. Some of these ape-like creatures continued to live successfully in the woods. But others were forced to leave the woods and go into the open fields of grass.
What works best for survival in the grasslands is different than what works best in the forest. Once our ancestors found themselves out of the woods, they couldn’t hide from predators as well, and food was not as plentiful. Many of these ape-like creatures living in the grasslands could not survive.
But some of these creatures did survive- those that could walk on two feet, for example. Walking on two feet may have helped them to run for longer distances to get away from predators. It also may have helped them to find food from further away and have free hands to carry it back home. Whatever the reason, those that could walk on two feet were surviving more often.
The ape-like creatures that could walk on two feet had kids that were also more able to walk on two feet (this is controlled by one’s DNA). So every generation, more and more of the surviving population could walk on two feet. The others got killed off by predators and/or starved to death.
Over many generations (and a few million years) living in separate places, we ended up with two different species. The ones in the grasslands walked on two feet, learned to make tools and work in groups, and eventually evolved into us. Those that stayed in the forest evolved into modern apes. Of course, those in the forest also changed after many years to survive better in the forest.
So there you have it. We didn’t evolve from apes; rather, apes and humans evolved from a common ancestor. Natural selection doesn’t care about whether a species is smarter or more progressive. It only cares about whether a species can survive long enough to find a mate and have kids.
Thus, the reason that modern apes are still around is that they have been successful at surviving in their environment. And we are still around because we have also been successful at living in our environment. Perhaps the most amazing thing is that after 5-8 million years, we still share 98% of the same DNA with our distant cousins, the modern apes!
Sources: Dr. Kim Matulef, Stanford University, PBS.org, Berkley.edu, me:)
Brain Evolution by Dwayne Godwin and Jorge Cham
(via: Scientific American magazine)
Public bathrooms can be pretty gross - but should you be worried about contamination? Science breaks down whether you should hover or cover the toilet seat.
Attention, science enthusiasts! If you’re looking for new science blogs to follow - here’s an excellent list: Part 1 Part 2
That amazing list was put together by the awesome Shychemist, check out his blog, help him expand the list!
Check out this great infographic the World Science Festival made about space debris. NASA and the U.S. Department of Defense work together to track some 21,000 pieces of man-made space junk, a tiny portion of the millions of objects estimated to be circling the Earth.
In which direction is the cube spinning? Now blink, or look away and look back. Is it still spinning in the same direction?
A Necker Cube is an ambiguous line drawing. Our brain can create different interpretations of it.
This clip was part of the Christmas Lectures 2011 presented by Professor Bruce Hood - Lecture One: What’s in your head? Watch it in full on the Ri Channel.
Many ideas have left the world of science and made their way into everyday language — and unfortunately, they are almost always used incorrectly. We asked a group of scientists to tell us which scientific terms they believe are the most widely misunderstood. Here are ten of them.
This is really helpful in getting to the nitty-gritty of those science concepts/words that seem like they mean one thing, but actually mean something different.
The Sixth Extinction
This chart shows the enormous uptick in species extinction over the last century.
Paul Ehrlich and others use highly conservative estimates to prove that species are disappearing faster than at any time since the dinosaurs’ demise.
There is no longer any doubt: We are entering a mass extinction that threatens humanity’s existence.
That is the bad news at the center of a new study by a group of scientists including Paul Ehrlich, the Bing Professor of Population Studies in biology and a senior fellow at the Stanford Woods Institute for the Environment. Ehrlich and his co-authors call for fast action to conserve threatened species, populations and habitat, but warn that the window of opportunity is rapidly closing.
“[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” Ehrlich said.
Although most well known for his positions on human population, Ehrlich has done extensive work on extinctions going back to his 1981 book, Extinction: The Causes and Consequences of the Disappearance of Species. He has long tied his work on coevolution, on racial, gender and economic justice, and on nuclear winter with the issue of wildlife populations and species loss.
There is general agreement among scientists that extinction rates have reached levels unparalleled since the dinosaurs died out 66 million years ago. However, some have challenged the theory, believing earlier estimates rested on assumptions that overestimated the crisis.
The new study, published in the journal Science Advances, shows that even with extremely conservative estimates, species are disappearing up to about 100 times faster than the normal rate between mass extinctions, known as the background rate.
“If it is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on,” said lead author Gerardo Ceballos of the Universidad Autónoma de México.
Using fossil records and extinction counts from a range of records, the researchers compared a highly conservative estimate of current extinctions with a background rate estimate twice as high as those widely used in previous analyses. This way, they brought the two estimates – current extinction rate and average background or going-on-all-the-time extinction rate – as close to each other as possible.
Focusing on vertebrates, the group for which the most reliable modern and fossil data exist, the researchers asked whether even the lowest estimates of the difference between background and contemporary extinction rates still justify the conclusion that people are precipitating “a global spasm of biodiversity loss.” The answer: a definitive yes.
“We emphasize that our calculations very likely underestimate the severity of the extinction crisis, because our aim was to place a realistic lower bound on humanity’s impact on biodiversity,” the researchers write.
To history’s steady drumbeat, a human population growing in numbers, per capita consumption and economic inequity has altered or destroyed natural habitats. The long list of impacts includes:
Now, the specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature, which maintains an authoritative list of threatened and extinct species.
“There are examples of species all over the world that are essentially the walking dead,” Ehrlich said.
As species disappear, so do crucial ecosystem services such as honeybees’ crop pollination and wetlands’ water purification. At the current rate of species loss, people will lose many biodiversity benefits within three generations, the study’s authors write. “We are sawing off the limb that we are sitting on,” Ehrlich said.
Image Source: International Union for Conservation of Nature
science-junkie
scienceyoucanlove-deactivated20
The Sixth Extinction
This chart shows the enormous uptick in species extinction over the last century.
Paul Ehrlich and others use highly conservative estimates to prove that species are disappearing faster than at any time since the dinosaurs’ demise.
There is no longer any doubt: We are entering a mass extinction that threatens humanity’s existence.
That is the bad news at the center of a new study by a group of scientists including Paul Ehrlich, the Bing Professor of Population Studies in biology and a senior fellow at the Stanford Woods Institute for the Environment. Ehrlich and his co-authors call for fast action to conserve threatened species, populations and habitat, but warn that the window of opportunity is rapidly closing.
“[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” Ehrlich said.
Although most well known for his positions on human population, Ehrlich has done extensive work on extinctions going back to his 1981 book, Extinction: The Causes and Consequences of the Disappearance of Species. He has long tied his work on coevolution, on racial, gender and economic justice, and on nuclear winter with the issue of wildlife populations and species loss.
There is general agreement among scientists that extinction rates have reached levels unparalleled since the dinosaurs died out 66 million years ago. However, some have challenged the theory, believing earlier estimates rested on assumptions that overestimated the crisis.
The new study, published in the journal Science Advances, shows that even with extremely conservative estimates, species are disappearing up to about 100 times faster than the normal rate between mass extinctions, known as the background rate.
“If it is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on,” said lead author Gerardo Ceballos of the Universidad Autónoma de México.
Using fossil records and extinction counts from a range of records, the researchers compared a highly conservative estimate of current extinctions with a background rate estimate twice as high as those widely used in previous analyses. This way, they brought the two estimates – current extinction rate and average background or going-on-all-the-time extinction rate – as close to each other as possible.
Focusing on vertebrates, the group for which the most reliable modern and fossil data exist, the researchers asked whether even the lowest estimates of the difference between background and contemporary extinction rates still justify the conclusion that people are precipitating “a global spasm of biodiversity loss.” The answer: a definitive yes.
“We emphasize that our calculations very likely underestimate the severity of the extinction crisis, because our aim was to place a realistic lower bound on humanity’s impact on biodiversity,” the researchers write.
To history’s steady drumbeat, a human population growing in numbers, per capita consumption and economic inequity has altered or destroyed natural habitats. The long list of impacts includes:
Now, the specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature, which maintains an authoritative list of threatened and extinct species.
“There are examples of species all over the world that are essentially the walking dead,” Ehrlich said.
As species disappear, so do crucial ecosystem services such as honeybees’ crop pollination and wetlands’ water purification. At the current rate of species loss, people will lose many biodiversity benefits within three generations, the study’s authors write. “We are sawing off the limb that we are sitting on,” Ehrlich said.
Image Source: International Union for Conservation of Nature
