The Future of Evolution: What Will We Become？

Charles Q. Choi, Special to LiveScience, LiveScience.com

Editor's Note: This is the last in a 10-part LiveScience series on the origin, evolution and future of the human species and the mysteries that remain to be solved. 

The past of human evolution is more and more coming to light as scientists uncover a trove of fossils and genetic knowledge. But where might the future of human evolution go? 

There are plenty of signs that humans are still evolving. However, whether humans develop along the lines portrayed by hackneyed science fiction is doubtful.

Cliches dashed

An old cliche has the highly evolved humans of the future sporting large heads to hold their advanced enlarged brains, "but that's nonsense, whole nonsense," said paleontologist Peter Ward at the University of Washington at Seattle, author of "Future Evolution."

"If you've ever gone through a childbirth or witnessed one," Ward says, "we're already anatomically right on the edge of how big our heads can go - our big brains have already caused extreme problems in childbirth, and if we had bigger and bigger brains, that'd cause more mothers to die in childbirth, so evolution would select against that."

Another idea, suggested by evolutionary theorist Oliver Curry of the London School of Economics, seems like a retread of ideas from science fiction writer H.G. Well's classic "The Time Machine," with the human species split in two over time - an underclass of dim-witted, short goblins, and a genetic upper class of tall, slim, healthy, attractive, intelligent and creative superhumans that eventually are spoiled by technology that will do everything for them, resembling domesticated animals.

"That's crap," Ward said. "Why would that happen? Are we like blind cavefish? After we get Google, do we get stupider? Intelligence is coded on too many genes to just lose a trait like intelligence. That's not going to happen."

As to whether humans will evolve to lose the arguably extraneous pinky for a cartoonish four-fingered hand, "that's crap," Ward said. "We've had five fingers for a long time. What aspect of natural selection would opt for four? Once a body plan seizes upon a number of digits, it doesn't change unless there's a damn good reason. It made sense for the horse to go down to a single hoof, but I can't think of why we would lose fingers."

Ward suggests that, if left untouched, humans might converge in appearance as populations mix. "I kind of view us all as eventually having chocolate-covered hair and medium stature, getting rid of all extremes," he speculated. "Of course, the big elephant in the room, the change from the past that you cannot ignore when talking about the future of human evolution, is genetic engineering."

Genetic engineering

Humanity now has an unparalleled means by which to direct our evolution - genetic engineering. By using viruses and other techniques, we can in theory modify our genomes, and over time, scientists may uncover genes underlying intelligence, health, athletic prowess, longevity and other desirable traits, engineering what might seem like superhuman progeny. Genetic engineering is how Ward speculated new species of humans might emerge.

"Let's say we create someone that can live 100 or 120 years," he said. "If you know you can live up to then, your whole pattern of investing could radically change. The amount of money that you could invest would go way, way, way up, and then economic incentives could drive selection away from mating with other creatures to seek out those similar to you."

Once populations are separated, given enough time and near-total lack of interbreeding, you would get divergence, he conjectured. Although short-lived humans could genetically engineer their own offspring for longevity, Ward suggested that interbreeding between populations would still remain low.

"I think taboos would arise which would prevent mating between populations - 'I don't want them anymore' or 'We want natural people,'" he said. "Of course this is all pure speculation, but this is the only way I can see new human species emerging - unless we get off the planet."

The final frontier

Another way new human species might occur is if we finally leave the cradle of our home world.

"If you want to make a new species, you have to really separate populations out," Ward said. "If we're all holed up on Earth, I don't see new species emerging, unless of course we engineer one. However, if we get some populations to split off by sending them off to space colonies, where they might evolve under different environments, it's possible."

The challenges entailed with leaving the solar system "could mean we might not ever colonize another star," Ward said. "But it could be that genetic engineering could make it possible."

Besides reducing human size to make travel easier on spaceship life support systems, Ward noted his colleague Mark Roth of the Fred Hutchinson Cancer Research Center in Seattle is conducting research to put humans into a hibernation-like state by having people inhale hydrogen sulfide.

"We might actually start selecting for the types of brain or nervous systems that allow one to go into hibernation," Ward said.

Our technology might readily spin us far past human shapes. Science fiction has long speculated as to whether or not we might one day be able to download our brains into computers or engineer bodies that can perform like spaceships.

"We're opening up new ways of evolving involved with machines," Ward said.

• Bionic Humans: Top 10 Technologies 
• Top 10 Things That Make Humans Special 
• Breakthroughs That Will Change Everything 

  http://news.yahoo.com/s/livescience/20091116/sc_livescience/thefutureofevolutionwhatwillwebecome;_ylt=Amm6OU1ASrbrewOTpaJ5ehYbr7sF

Human Evolution: The Origin of Tool Use

Charles Q. Choi, Special to LiveScience 

Editor's Note: This is Part 8 in a 10-part LiveScience series on the origin, evolution and future of the human species and the mysteries that remain to be solved.

The way humans make and use tools is perhaps what sets our species apart more than anything else. Now scientists are more and more uncovering the forces that drove our lineage to our heights of tool use — and how tool use, in turn, might have influenced our evolution.

The first stone tools — the Oldowan 

The ability to make and use tools dates back millions of years in our family tree. Chimpanzees, our closest living relatives, can on their own devise spear-like weapons for hunting and create specialized tool kits for foraging ants, suggesting our family tree may have possessed wooden tools since the ancestors of humans and chimps diverged some 4 million years ago.

The dawn of stone tools dates back some 2.6 million years to Gona in Ethiopia. Known as the Oldowan, these include not just fist-sized hunks of rock for pounding, but also the first known manufacture of stone tools — sharp flakes created by knapping, or striking a hard stone against quartz, obsidian, flint or any other rock whose flakes can hold an edge. At this time are also the oldest known butchered animal bones.

"So the hominids at this time, based on all the evidence that we have, had small australopithecine-sized brains, but nevertheless they figured out how to cut through often tough hide to efficiently get the meat off the bones and break the bones open for the marrow," said paleoanthropologist Henry Bunn at the University of Wisconsin at Madison.

This was the extent of the technology for nearly a million years. "It was probably very ad hoc — when you needed a stone tool and you didn't have one, just made one, then dropped it," said paleoanthropologist Thomas Wynn at University of Colorado at Colorado Springs.

Such technology is just slightly past the range of what apes generally do, Wynn added. Indeed, chimpanzees in the wild can use stones as simple tools for hammering, and the chimpanzee-like bonobo ape can even be taught how to flake stone to make cutting tools. "These don't seem to represent any great intellectual leap," he said.

The appearance of stone tools falls roughly in the middle of a drying trend in Africa between 2 million and 3 million years ago that would have presented our distant ancestors with a greater variety of habitats than they would have known before, such as woodlands to grasslands, explained paleoanthropologist Thomas Plummer at Queens College in New York. "Tools may have allowed hominids to be more adaptable, extract food from a greater range of areas," he said.

A great advance in technology — the Acheulean 

Jump ahead to roughly 1.8 million years ago and both technology and our lineage have changed.

"You now have rough hand axes and cleavers," Wynn said. "The technology is really different, more sophisticated in a cognitive way than anything earlier hominids or chimpanzees could do — some see cognitive abilities to coordinate spatial and shape information that chimpanzees don't have. This is the beginning of what we call the Acheulean."

At about that time, Homo erectus has emerged. "Finally all the adaptations for arboreal life have gone," Wynn said. "Erectus has gone completely terrestrial — not climbing trees very much at all."

In addition, "Homo erectus has started carrying tools around, instead of dropping them after use," Wynn said. "Technology has become part of their adaptive niche, a more or less permanent day-to-day thing relied on regularly. It's all tremendously significant from a cognitive point of view. I would place all this as an even more significant transition than the initial use of stone tools."

Meat and evolution 

Homo erectus evolved in ways "to make getting access to meat and efficiently digesting meat more successful — you've got increased brain size, about two-thirds that of the modern human average, and increased body size," Bunn said. "You've also got a reduction in gut size, so you can devote the resources that would normally go there toward a bigger brain, as well as this high-energy brain food of meat to support those large brains."

This doesn't mean that early stone tools were restricted to just processing animal carcasses, Bunn noted, "or that meat became a dominant factor in their lives, since by all indications, from chimpanzees to tropical hunter-gatherer people today, plants are the dominant day-to-day part of the diet. It just shows an increased interest in meat."

Technology and society 

As tool use evolved, "somewhere along the line, there had to have been really important changes in social evolution," Wynn said.

Scientists argue, for instance, when provisioning or the sharing of food began. "In Homo erectus, you see an increase in female size, which some argue suggests that infants are born less mature, thus requiring more maternal care. So the suggestion is that provisioning helps females find something to eat."

There are two ideas regarding provisioning. One is that males are the ones bringing food over due to pair-bonding between the sexes. Another is the "grandmother hypothesis," where grandmothers bring their daughters food to help them raise their offspring. "The problem with that is that with all male African apes, females leave groups at adolescence, so the grandmother hypothesis would represent a pretty dramatic change socially," Wynn said.

Still, Wynn noted other research has suggested primates spread throughout the Old World do possess these female links, "and Homo erectus has a very different distribution from the African apes, were distributed more widely in Africa and Asia, and so maybe Homo erectus mimics the behavior of these other primates. Also, the new fossil Ardipithecus tells us our ancestors may not have been very much like chimps and gorillas, so maybe socially we were not as alike as well."

Windows into the brain 

Now scientists are using stone tools as windows to help investigate how the brains of the human family tree evolved over time.

"What was it these early stone-knappers knew that chimpanzees can't get?" Wynn asked. "I think one thing was that early hominids were much better at copying motor procedures — we can watch an individual perform a motor task and mimic it. Chimpanzees are terrible at that — they see a task and have to reinvent the wheel. This gets back to mirror neurons and the copying of behavior."

"Tools are the products of our brains, and we have millions of stone tools," Wynn added. What we need are more creative ideas on how to extract understanding from them, and what they tell us about our evolution."

• Top 10 Mysteries of the First Humans
• Poll: Your View of Human Evolution
• Top 10 Things That Make Humans Special

http://www.livescience.com/health/091111-origin-tool-use.html

Humans Still Evolving as Our Brains Shrink

Charles Q. Choi, Special to LiveScience, LiveScience.com

Editor's Note: This is Part 9 in a 10-part LiveScience series on the origin, evolution and future of the human species and the mysteries that remain to be solved.

Evolution in humans is commonly thought to have essentially stopped in recent times. But there are plenty of examples that the human race is still evolving, including our brains, and there are even signs that our evolution may be accelerating.

Shrinking brains

Comprehensive scans of the human genome reveal that hundreds of our genes show evidence of changes during the past 10,000 years of human evolution.

"We know the brain has been evolving in human populations quite recently," said paleoanthropologist John Hawks at the University of Wisconsin at Madison.

Surprisingly, based on skull measurements, the human brain appears to have been shrinking over the last 5,000 or so years.

"When it comes to recent evolutionary changes, we currently maybe have the least specific details with regard the brain, but we do know from archaeological data that pretty much everywhere we can measure - Europe, China, South Africa, Australia - that brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10 percent," Hawks said.

"As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much," he added.

Mutations against malaria

In contrast to our limited but growing knowledge regarding the modern evolution of the human brain, the best example we see of evolution of humans in recent history is linked with malaria, Hawks said. Since the disease often targets humans early in life, there was a strong pressure to evolve defenses from malaria - any genetic factor that confers resistance against it would give descendents a chance to have offspring, while those without such protection were more likely to not reproduce.

There are lots of examples of defenses against malaria. Sickle cell anemia is the best known -the disorder deforms red blood cells into sickle shapes, which can impair blood flow, thus damaging tissues, this malformation also prevents the malaria parasite from infesting blood cells.

"Although sickle cell is best known in Africa, there is also an India-Pakistan variant of it that seems to have evolved separately," Hawks explained. "Both variants have evolved very recently, in the last three or four thousand years, and in that time have risen to as much as 10 to 15 percent of the populations. That's pretty rapid change."

Food and drink

Lactose tolerance is another recent example of a recent evolutionary change.

Most of the world remains lactose intolerant, unable to digest the complex milk sugar lactose as adults, but the evolution of lactose tolerance perhaps some 7,500 years ago in Europe enabled people there to take advantage of non-human milk, a highly nutritious food source one can sustainably procure instead of slaughtering animals.

Other evolutionary changes linked with diet appear to deal with genes conferring protection against type II diabetes.

"When you develop agricultural diets, you might need adaptations to survive on them, the way the digestive systems are regulated," Hawks said.

Is our evolution accelerating?

There are signs that human evolution may not only be continuing, but that its rate has even accelerated in recent times. Hawks and his colleagues have found evidence of rapid change, with a host of new mutations originating in the last 40,000 years.

So what might explain this apparent acceleration?

"The ecology of humans has been changing," Hawks said. "The biggest changes have to do with agriculture and its consequences - dealing with a new subsistence pattern that caused people to rely on foods that were never very important before, a radical shift from hunter-gatherer diets. For instance, agricultural populations tend to have more copies of a gene for salivary amylase, which helps them digest starch."

Top 10 Mysteries of the First Humans

Poll: Your View of Human Evolution

Top 10 Things That Make Humans Special 

http://news.yahoo.com/s/livescience/20091113/sc_livescience/humansstillevolvingasourbrainsshrink;_ylt=AgoHdPQhzyUIjFjv5LKAj7kbr7sF

Human Origins: Our Crazy Family Tree

Charles Q. Choi, Special to LiveScience, LiveScience.com

Editor's Note: This is Part 7 in a 10-part LiveScience series on the origin, evolution and future of the human species and the mysteries that remain to be solved.

As the only remaining primate built to stride the world on two legs, it would be easy to assume that our extinct relatives were much like us, if perhaps hairier with smaller brains.

But fossils reveal evolution could take our relatives in bizarre directions, involving skulls resembling nutcrackers and miniature bodies resembling the hobbits of Lord of The Rings.

"These fossils tell us that human evolution was a long process of experimentation, not the outcome of a long process of fine-tuning leading just to us," said paleoanthropologist Ian Tattersall at the American Museum of Natural History in New York.

Nutcracker Man

When the first members of the human family tree, Homo, emerged roughly 2.5 million years ago, they were not the only bipedal primates roaming Africa. We shared the landscape with a relative with big mouths built for chomping - one commonly dubbed "Nutcracker Man."

"This is a creature very much like us that is competing with us, that is shaping our evolution just as we are shaping theirs," said paleoanthropologist John Hawks at the University of Wisconsin at Madison.

Just as humans might, Nutcracker Man - more formally known as Paranthropus boisei - likely descended from slender bipeds known as the gracile australopithecines, which include the famed 3.2-million-year-old fossil Lucy. "They're small-brained compared to Homo, but if you look at australopithecines, it has the biggest brains of any of them," Hawks said.

However, the skulls of Nutcracker Man and other so-called robust australopithecines were quite different from ones seen in the human family tree. They boasted huge jaws, big crests on top of the skull for giant chewing muscles, and large flat teeth with highly thickened enamel on them.

Paranthropus was always thought of as the quintessential nutcracker, but recent analyses of their teeth suggest it might strangely have preferred to eat a broad diet with squishy fruits.

"So why have giant teeth?" Hawks said. "The most popular idea is the 'fallback' notion, that at certain times you have to fall back on foods that wear on teeth, so the kind of stuff with grit."

"That doesn't quite seem totally satisfactory to me," Hawks added. "We think of them having big teeth, but really only the molar and pre-molar teeth are big, while their incisors and canines are teeny-tiny, much smaller than in humans, and you'd want to retain incisors if you're taking husks off fruit. So maybe they are specialized after all - there was interesting research into them eating papyrus roots, living in swampish places."

The Hobbit

For years, the people of the Indonesian isle of Flores had legends of the Ebu Gogo - small, hairy cave-dwellers. Hardly anyone took these myths seriously until 2003, when diminutive skeletons with oversized feet and small chimp-sized brains were discovered there, which apparently survived until as recently as 12,000 years ago.

Scientists conjecture the creature, which stood about 3 feet 5 inches tall and weighed roughly 70 lbs., evolved its miniature size in response to its island home, where resources can often be limited - a phenomenon seen previously in many other animals, including dinosaurs, but not humans. Many of its features, such as the shoulder, wrist, jaw and teeth, are primitive, more closely resembling earlier australopithecines than modern humans. Still, it apparently walked upright and made stone tools, and some evidence suggests that it may have hunted and used fire.

Is the 'hobbit,' as even scientists call them, in fact an extinct human species, enough to be called Homo floresiensis?

Are these skeletons just examples of stunted versions of Homo sapiens?

Are they a different species but perhaps not a human one, instead as separate as chimpanzees are?

These are the questions raging now over these skeletons among scientists.

"What do the hobbit show us?" Hawks asked. "If they are a human species, then it reveals that there isn't this inevitable progress toward big brains and more technological sophistication. It's very possible for humans to go off in a different direction."

"With these side branches, you get a sample of the different ways there are of being a hominid, but it could speak more about our evolution as well," Hawks added. "The fact that we stuck around when others didn't could be because of how we heavily leaned on technology in ways that earlier hominids didn't. Maybe that's what it took to survive this rat race."

• Top 10 Mysteries of the First Humans
• Poll: Your View of Human Evolution
• Top 10 Things That Make Humans Special 

  http://news.yahoo.com/s/livescience/humanoriginsourcrazyfamilytree;_ylt=AmpBvdVlWncolRXlrNpcS2Ebr7sF