Ancestors of Modern Day Humans Came Down From the Trees to Become Bipedal

In the Aug. 10th 2009 issue of the journal Proceedings of the National Academy of Sciences, researchers have postulated that "early humans walked on their knuckles before evolving the ability to walk upright, but a new study suggests they may have bypassed that step"

Researchers have developed their ideas from their detailed examination of "the wrist bones of several primate species, and found that humans more likely evolved from a tree-climbing ancestor, rather than a knuckle-walking one. The new model reignites a longstanding debate about the origin of walking on two legs, or bipedalism, in humans."

Scientists believe that: "Since humans' closest living relatives, the African apes, often move around on knuckles and legs, many experts thought human ancestors may have also employed knuckle-walking. But another camp of scientists traces humans' two-legged walking to earlier tree-climbing, a mode of locomotion that is used by all living apes."

Analysis provided by "evolutionary anthropologist Tracy Kivell of Duke University compared juvenile and adult wrist bones of chimps and bonobos, our closest living primate kin, with those of gorillas."

Dr. Kivell "found two key bone features associated with knuckle-walking in 96 percent of adult chimpanzees and 76 percent of bonobos, but in only 6 percent of the gorilla specimens she studied."

Researchers have suggested that "one explanation for the absence of these features in gorillas is that they knuckle-walk in a fundamentally different way from chimps and bonobos. Gorillas stride with their arms and wrists extended straight down, while chimps and bonobos walk more flexibly with their wrists bent."

"We sat down together and asked, 'What are the differences between them?'" said co-researcher Daniel Schmitt. "The answer," Schmitt explained, is "that chimps and bonobos spend a lot of time in the trees. And gorillas do not."

Researchers "Kivell and Schmitt think this suggests that knuckle walking evolved independently in the two African ape lineages. The researchers also think that some features of the hand and wrist found in the human fossil record that have traditionally been treated as indicators of knuckle-walking behavior are more likely to be related to tree climbing."

The evidence suggests that the ancestors of humans climbed in trees, and then eventually moved to the ground and began walking upright, the researchers said."

"We have the most robust data I've ever seen on this topic," Schmitt said. "This model should cause everyone to re-evaluate what they've said before."

"There are no fossils from the time of this transition, which likely occurred about seven million years ago, Kivell and Schmitt said."

Our Insignificance: Using Historical Method

We are insignificant creatures.

The evolution of modern human beings stretches back into our planets past a mere 250 million years; an insignificant scratch on the Earth's surface when we consider that life began some 3.85 billion years ago on a planet that is some 4 billion years old. But before we become lost in the minutiae of discussing ancient bacterial life with the human genesis that we are a direct descendant of today let us consider the paradox of time that for the most part eludes human consciousness concerning origins viewed from the panorama of Earth's incomprehensible length of history.

What I am alluding to is of course the recognition of geological or deep time which has washed over humankind's significance in the universe like a giant wave that powerfully sweeps across and engulfs an island bound piece of land. The impact of the discovery of deep time initiated the dethronement of God from the center of the universe. With God gone, man stood alone to understand and create humanity's place in the universe. And it created a secular consciousness in the minds of human beings that forced our species to acknowledge responsibility for what takes place in the course of human affairs and events and place it squarely on the shoulders of humankind. Simultaneously we became a happenstance creation in an infinite universe with the handicap of only being able to represent reality by rounding off the edges, seeking out the longue durée, and confronting the problems associated with our biased perceptions of all that is etched on our consciousness.

The problem, of course, with having such ultimate powers of representation is that we are forced to draw a comprehensible explanation which our senses relate to us and then explain that perception to fellow human beings. For those who try to walk the tightrope of representation; they must deal with the foibles of their own abilities to represent a reality that is struck between their own significance and insignificance as mortal beings. It is inevitable that self-doubt permeates our self confidence.

The significance of this observation is that we as observers cannot escape drawing conclusions from what we are focused on. And while we are focused on our observations, we might as well approach them in a systematic manner. And don't forget, human beings, although making observations of current, complex phenomena are doing so with brains that are no different in composition from those of our ancestors of some five thousand years ago.

The answer to our individual shortcomings is to widen our range of collective experiences to extend beyond that which an individual can take in and encounter by using the experiences of others who have confronted comparable instances in the past with the theory being that by taking such an approach, humanity's chances of drawing conclusions with greater wisdom would increase proportionately.

But what of other methods of observation including religion, culture, tradition, environment, and technology? Isn't historical observation lacking in responsiveness and authority when compared to these other areas of human endeavors? The problem is disputed easily when one considers that religion and culture are so dominated and answerable to orthodoxies, while human beings are highly adaptable creatures and make technology and environment less dependable as markers of human activities. Finally, traditions exist as manifestations without any solid consistency. This leaves historians with the sole task of providing interpretations of the past from the present to shape the course of the future. But do not let us venture too far afield: Studying the past guarantees no sure method of predicting the future. All that history can hope to accomplish is to prepare humanity for an uncertain future contained within certain bounds of past familiarities and humanizes the vagaries of deep time upon human consciousness and it's limitations.

Why Free Scientific Inquiry and Democracy are Inexorably Linked and Indicate the Intellectual Health of our Nation

Ask any group of common American citizens about what they think about evolution and the odds are quite high that 46% of those polled will completely reject the tenets and existence of evolution. In fact, some of those polled may be so bold as to indicate that they believe that the facts for evolution espoused by Darwin and his later day followers make this group of scientific eggheads hard boiled and tools of the devil.

Roughly the same sized group of contemporary Americans, I'm not talking about those who lived sometime in the early nineteenth century, would also contend that the Earth is actually less than 10,000 years old. If you will remember from an earlier posting I made this week the actual age of the Earth is really closer to 4 billions years old.

Why are so many people so dumb one might wonder? Well there's plenty of blame to go around and a lot of it has to do with the way science is ignored by the popular media. No. I'm not talking about that next shuttle mission launch; that's important and newsworthy because you never know when one of those overused old workhorse shuttles might explode on launch or upon reentry into the Earth's atmosphere - that's your media in action; covering the spectacle while ignoring the every-day occurrences of science and its intertwining with the strength of our fledgling democracy.I'm talking about the plain fact that over the past several decades, weekly science sections in daily newspapers has shrunken by an astonishing 2/3 of what they once were. Current debates over such significant topics as global climate change have been shifted from a discussion of scientific facts and theories and place into the arena of political bigotry. In addition the voice of scientists have been muted by those of popular religious leaders and opinion makers, groups who do not rely on scientific findings to base their views but on the means and methods of propaganda to support their agendas.

An important insight into the morass in discussing scientific subjects was predicted in the famous 1959 Rede lecture at Cambridge University by C. P. Snow, a scientifically trained writer who uncovered the existence of the competition between "two cultures" that was distinguishable by a "gulf of mutual incomprehension" that pitted humanists against scientists. As the holders of power and the decision makers in western society humanists held sway over the way science would be viewed. In comparison to the humanists, the members of the scientific community were marginalized and held little prestige; they were the 'specialists' who provided the means, such as nuclear weapons for the humanists to be the agenda setters. Meanwhile, the humanists had little practice understanding of what the scientists were capable of producing; they only knew that what ever might be produced could and would be put to use in the plans the humanists had assembled. With numerous threats facing humankind, from climate change;

to pandemics; and the spread of nuclear weapons; each of which are laden with scientific fundamentals that few if many non-scientists understand.

What is the connection to democracy you ask? It lies with the free and unimpinged flow of information and knowledge. The simple matter of the fact is that we live in an age increasingly dominated by science and scientific principles which constitute nothing but meaningless jargon not only for most of the population but also for our political, cultural, and legal gatekeepers as well as the leaders of capitalist enterprises. it is time we integrate a much more precise and meaningful understanding of the necessary integration of the scientific understanding of human affairs as an integral part of civic discourse. In other words the construction of a civics that welds a scientific understanding of worldly affairs with democratic principles that involve all citizens in this undertaking.

Texas Board of Education Weighs Validity of Science That Supports Evoutionary Knowledge

The battle between creationists and the supporters of Darwinianism can be boiled down to whether a textbook;

which includes the wording "strengths and weaknesses" as standards for teaching high school students creationism, intelligent design and evolution on an equal basis.

Explore Evolution

It has been learned that: "A closely watched effort to keep a 20-year-old requirement that Texas public high school students evaluate the "strengths and weaknesses" of scientific theories, including evolution, failed Thursday in a 7-7 vote by the State Board of Education," effectively ending the effort of the coalition of anti-Darwinist forces who sought to keep the "strengths and weaknesses" language in the high school classrooms.

"Supporters of evolution had assailed the 20-year-old "strengths and weaknesses" clause as a back door to teaching biblical creationism, while evolution-only critics spoke of weaknesses in Darwinian theory."

Eugenie C. Scott of the National Center for Science Education talks with Geraldine Miller and is shown answering how the inclusion of the "strengths and weaknesses" argument could adversely affect the content of textbooks produced in Texas and used throughout the southern portion of the United States including California.

The issues and the subsequent vote were so complicated and controversial, that a number of different news organizations reported differing views the final vote:

"The 13-2 vote removes current requirements that students be taught the “strengths and weaknesses” of scientific theories. Instead, teachers will be required to have students scrutinize “all sides” of scientific theories, a move criticized by evolution proponents." (The Austin American-Statesman)

"The Texas Board of Education voted today by a 13-to-2 margin to change controversial language in the state's curriculum, making it harder for creationism to creep into public classrooms. For the past 20 years, the state's curriculum has instructed teachers to present the "strengths and weaknesses" of scientific theories, opening the door to non-scientific, faith-based alternatives." (The Scientific American)

"Social conservatives lost another skirmish over evolution Friday when the State Board of Education stripped two provisions from proposed science standards that would have raised questions about key principles of the theory of evolution." (The Dallas Morning News)

"After six hours of often mind-numbing debate, the State Board of Education has mercifully passed a final version of new science standards that will guide the content of science textbooks and curriculum for the next decade." (The Texas Observer)

"In a string of amendments proposed after the compromise, the board adopted subtle changes that critics say cast a shadow over key tenets of the theory of evolution — natural selection and common ancestry."

"The document still has plenty of potential footholds for creationist attacks on evolution to make their way into Texas classrooms," said Kathy Miller, president of the watchdog group Texas Freedom Network. "Through a series of contradictory and convoluted amendments, the board crafted a road map that creationists will use to pressure publishers into putting phony arguments attacking established science into textbooks."

"We appreciate that the politicians on the board seek compromise, but don't agree that compromises can be made on established mainstream science or on honest education policy."

"Federal courts have ruled against teaching creationism and the similar theory of intelligent design in public schools."

"Supporters of the changes applauded efforts to encourage critical thinking in science classrooms.

Humanity is still Evolving

Modern human beings are involved in an ongoing process of evolution brought about humanities adaptation to environmental and cultural processes.

Humanity is not done evolving. Because in many instances, evolution seems to the unobservant individual to not be happening at all. It is a common belief to view human beings as fully evolved and as a 'completed' species.

One could not be further from the truth. Why is this so? It has to do with natural selection and its ongoing process of constantly defining the shape of the human gene pool.

A particular characteristic of a gene pool is that it locates the comprehensive genetic diversity of a species. This involves the biological discipline of genetics, which is the scientific study of heredity and variation in living organisms involving the inheritance of traits found in the parents of the living thing being studied.

Charles Darwin's The Origin of Species investigated why the genetics of a species can change over a long period of time. Darwin's extensive study of the reasons why such a change occurs over time advanced the meaning and significance of the theory of evolution.

Now a trip back to the gene pool is in order because when discussing evolution, it has been found that over periods of time, evolution favors the most desirable genes or characteristics in the pool. With the passage of time, these preferable characteristics gain an exclusive, or dominant place within the gene pool.

There are several factors that can effect the process of altering the structure of the gene pool.

The first factor that can have an altering effect on the structure of the gene pool describes a process in which genes that are more suited to their environment are favored and is called natural selection.

A Second altering effect on the gene pool, called mutation involves random processes that can result in changing the genome of a living thing.

Gene migration happens when genetic drift (a process of change in the genetic composition of a population takes place because of some random event or occurrence of chance, as opposed to natural selection, takes place) happens when two groups of a single species separate or move apart over time and reproduce separately. It is possible, if the two groups come back together and are able to reproduce then their genetic differences could merge and thereby create a greater genetic diversity (measures the level of the variation of life forms within a given ecosystem, biome, or the Earth as a whole; also known as biodiversity) refers to the total number of genetic characteristics in the genetic makeup of a species.

Non-Random Mating involves continuous inbreeding of a species and is more commonly referred to as selective breeding. These process allows the researcher to favor advantageous genes over less advantageous genes and results in the decreasing of genetic diversity.

When geographical events occur that result in the splitting apart or isolation of a species leaving the separated groups apart and unable to reproduce with one another, it is a process called Genetic Drift. With the groups living apart, natural selection will occur causing quite a dramatic difference in the gene pools of the separated species and over time might result in the creation of entirely different species.

Speciation is the process that happens when one species separates over time and reproduce within the isolated groups for such a long time that if the split-apart groups come together their genetic differences have become so significant that reproduction can no longer occur.

The process of Adaptive Radiation describes a slow change of genotype (the entire set of genes contained within a living thing) and phenotype ( the process of producing visible or measurable genetic traits such as skin color, height, behavior, etc, according to the individual's genetic makeup and the effect of the environment.

Cultural processes concern the uninterrupted developmental sequence of changes of properties or attributes of a human created systems that encompass all human phenomena that are not purely results of human genetics; thus regarding culture from it's simplest, or non-branched form to more complex forms that display a tendency of weaving together or encompassing an array of diverse creations from homogeneous elements showing uniformity to heterogeneous, or varied qualities

So as this brief overview of the numerous processes that can involve the evolution of any living things including human beings has shown: evolution is a continuing and ongoing process that is affected by several factors; any of which could cause a change in a species gene pool and result in the process of adaptation to environmental and cultural processes.

Pink Iguanas Missed by Darwin Are Discovered and Unexpectedly Rewrite the Evolutionary Genealogy of Galapagos Iguanas

HENRY FOUNTAIN of the New York Times writes that: “Charles Darwin was about as keen an observer of nature as ever walked the earth, but even he missed the pink iguana of the Galapagos. The rare land iguanas were first seen, in fact, only in 1986, when one was spotted by park rangers on Volcan Wolf on the island of Isabela. Since then they have been found only on that volcano, which would explain why Darwin missed them, since he didn’t explore it.” Researchers have determined “that the pink iguana is distinct from the two recognized species of land iguana on the Galápagos.” The species of pink iguana, have been determined by scientists to be genetically-distinct and represent a split from their green. Researchers have named the rare iguana after the Spanish word for pink—rosada. Alexis Madrigal, writing in the WIRED SCIENCE BLOG quotes scientists studying the new iguana who remark that “this form, which we recognize as a good species, is very important because it carries substantial evolutionary legacy," the authors of a new paper in the journal Proceedings of the National Academy of Sciences wrote. "Thus far the rosada form is the only evidence of deep diversification along the Galapagos land iguana lineage." Madrigal explains: “What” the researchers “found was surprising. Instead of being some slight variation on the Galapagos iguana theme, the pink lizards represent a distinct and early branch of the genetic tree. The genomic analysis of the species suggests a much deeper in history than most other Galapagos species, like Darwin's finches. In addition to the genetic differences, the pink iguanas also perform the characteristic mating ritual "head-bob" differently. Richard Black of the BBC elaborates on the differing movement of the head: “Iguanas typically bob and duck when they meet each other - a behaviour thought to be important for marking territory and courtship - and rosada does so in a more complex fashion than the yellow-coloured subcristatus or the other Galapagos species, Conolophus pallidus. It also has a different shape of crest. There is little sign of cross-breeding between pink and yellow. And the DNA analysis shows it is far more distinct from all the other land iguanas than they are from each other. That means the line that led to subcristatus and pallidus must have diverged from that leading to rosada long ago, with the split between subcristatus and pallidus coming much later. The DNA work puts the date of divergence between rosada and the rest at about 5.7 million years ago, raising a new set of questions,” explained Black."At 5.7 million years ago, all of the western islands of the archipelago did not exist," said Gabriele Gentile from the University of Rome Tor Vergata, who led the new analysis: "That's a conundrum, because it's now only inhabiting one part of Isabela that formed less than half a million years ago," he told BBC News. Black continues: “Even the oldest parts of the archipelago may be less than five million years old. The explanation may be that some volcanoes that are now under water were above it at the time when the first iguanas arrived, and this allowed some of the creatures to climb onto land and begin their separate evolution. Earlier DNA analysis suggests that land-based iguanas split from their marine counterparts about 10 million years ago.” Greg Laden adds: "The Galapagos are way over eight to ten million years old, and some time back around then were inhabited by iguanas from somewhere. Now keep in mind that the landscape looked pretty different back then. North and South America were not joined by the Panama land bridge, and there was probably a lot of movement of fauna and flora between what is now the eastern equatorial Pacific and the Caribbean. Land iguanas have always moved from island to island on a very low level in the Galapagos. Islands have slowly formed, grown large, then shrank, and slipped beneath the sea over time. But the temporal scale of island formation and disappearance is probably much slower than the temporal scale of iguana movement between islands. Furthermore, it is possible that inter-island movement becomes more likely when the islands become smaller, for ecological reasons." Unfortunately, Madrigal adds: “The iguana and other animals on Volcan Wolf are threatened by an "invasion of feral goats" that are devastating the area's natural flora. In the interest of preserving this genetic diversity, the biologists wrote that "a conservation program aimed at evaluating the risk of extinction of this newly recognized species," should be initiated. They estimate that the iguana could already by termed "critically endangered."

Captivating Evidence of Evolution

Brandon Keim, writing in the WIRED SCIENCE BLOG posts an entry based on the work of “the editors of Nature (who) compiled a selection of especially elegant and enlightening examples of evolution. The Nature editors explain that the goal of their endeavor is “for those wishing to spread awareness of evidence for evolution by natural selection." And is presented at a time when numerous skeptics continue their battle against the global acceptance of evolution. Keim adds that the twelve examples of evolution play a role that goes beyond the often dry and uninspiring findings of science. “They are, quite simply, wondrous — glimpses through an evolutionary frame of life's incredible narrative, expanding to fill every possible nook and cranny of Earth's biosphere. The examples provided by Nature succeed by “stir(ring) passion about the scientific validity of evolution without first captivating minds and imaginations. And this is a fine place to start.” So point your browser to this link that I’ve provided and dare yourself to consider the wondrous creation that evolution has brought to the Earth.