70 Million Years of Primate Evolution

70 Million Years of Primate Evolution Many people take an understandably human-centered view of primate evolution, focusing on the bipedal, large-brained hominids that populated the jungles of Africa a few million years ago. But the fact is that primates as a whole - a category of megafauna mammals that includes not only humans and hominids, but monkeys, apes, lemurs, baboons, and tarsiers - have a deep evolutionary history that stretches as far back as the age of dinosaurs. (See a gallery of prehistoric primate pictures and profiles.) The first mammal that paleontologists have identified as possessing primate-like characteristics was Purgatorius, a tiny, mouse-sized creature of the late Cretaceous period (just before the K/T Impact Event that rendered the dinosaurs extinct). Although it looked more like a tree shrew than a monkey or ape, Purgatorius had a very primate-like set of teeth, and it (or a close relative) may have spawned the more familiar primates of the Cenozoic Era. (Genetic sequencing studies suggest that the earliest primate ancestor may have lived a whopping 20 million years before Purgatorius, but as yet theres no fossil evidence for this mysterious beast.) Scientists have touted the equally mouse-like Archicebus, which lived 10 million years after Purgatorius, as the first true primate, and the anatomic evidence in support of this hypothesis is even stronger. Whats confusing about this is that the Asian Archicebus seems to have lived around the same time as the North American and Eurasian Plesiadapis, a much bigger, two-foot-long, tree-dwelling, lemur-like primate with a rodent-like head. The teeth of Plesiadapis displayed the early adaptations necessary for an omnivorous diet - a key trait that allowed its descendants tens of millions of years down the line to diversify away from trees and toward the open grasslands. Primate Evolution During the Eocene Epoch During the Eocene epoch- from about 55 million to 35 million years ago- small, lemur-like primates haunted woodlands the world over, though the fossil evidence is frustratingly sparse. The most important of these creatures was Notharctus, which had a telling mix of simian traits: a flat face with forward-facing eyes, flexible hands that could grasp branches, a sinuous backbone, and (perhaps most important) a bigger brain, proportionate to its size, than can be seen in any previous vertebrate. Interestingly, Notharctus was the last primate ever to be indigenous to North America; it probably descended from ancestors that crossed the land bridge from Asia at the end of the Paleocene. Similar to Notharctus was the western European Darwinius, the subject of a big public relations blitz a few years back touting it as the earliest human ancestor; not many experts are convinced. Another important Eocene primate was the Asian Eosimias (dawn monkey), which was considerably smaller than both Notharctus and Darwinius, only a few inches from head to tail and weighing one or two ounces, max. The nocturnal, tree-dwelling Eosimias - which was about the size of your average Mesozoic mammal - has been posited by some experts as proof that monkeys originated in Asia rather than Africa, though this is far from a widely accepted conclusion. The Eocene also witnessed the North American Smilodectes and the amusingly named Necrolemur from western Europe, early, pint-sized monkey ancestors that were distantly related to modern lemurs and tarsiers. A Brief Digression - The Lemurs of Madagascar Speaking of lemurs, no account of primate evolution would be complete without a description of the rich variety of prehistoric lemurs that once inhabited the Indian Ocean island of Madagascar, off the east African coast. The fourth-largest island in the world, after Greenland, New Guinea, and Borneo, Madagascar split off from the African mainland about 160 million years ago, during the late Jurassic period, and then from the Indian subcontinent anywhere from 100 to 80 million years ago, during the middle to late Cretaceous period. What this means, of course, is that its virtually impossible for any Mesozoic primates to have evolved on Madagascar before these big splits- so where did all those lemurs come from? The answer, as far as paleontologists can tell, is that some lucky Paleocene or Eocene primates managed to float to Madagascar from the African coast on tangled thatches of driftwood, a 200-mile journey that could conceivably have been accomplished in a matter of days. Crucially, the only primates to successfully make this trip happened to be lemurs and not other types of monkeys - and once ensconced on their enormous island, these tiny progenitors were free to evolve into a wide variety of ecological niches over the ensuing tens of millions of years (even today, the only place on earth you can find lemurs is Madagascar; these primates perished millions of years ago in North America, Eurasia, and even Africa). Given their relative isolation, and the lack of effective predators, the prehistoric lemurs of Madagascar were free to evolve in some weird directions. The Pleistocene epoch witnessed plus-sized lemurs like Archaeoindris, which was about the size of a modern gorilla, and the smaller Megaladapis, which only weighed 100 pounds or so. Entirely different (but of course closely related) were the so-called sloth lemurs, primates like Babakotia and Palaeopropithecus that looked and behaved like sloths, lazily climbing trees and sleeping upside-down from branches. Sadly, most of these slow, trusting, dim-witted lemurs were doomed to extinction when the first human settlers arrived on Madagascar about 2,000 years ago. Old World Monkeys, New World Monkeys and the First Apes Often used interchangeably with primate and monkey, the word simian derives from Simiiformes, the infraorder of mammals that includes both old world (i.e., African and Eurasian) monkeys and apes and new world (i.e., central and South American) monkeys; the small primates and lemurs described on page 1 of this article are usually referred to as prosimians. If all this sounds confusing, the important thing to remember is that new world monkeys split off from the main branch of simian evolution about 40 million years ago, during the Eocene epoch, while the split between old world monkeys and apes occurred about 25 million years later. The fossil evidence for new world monkeys is surprisingly slim; to date, the earliest genus yet identified is Branisella, which lived in South America between 30 and 25 million years ago. Typically for a new world monkey, Branisella was relatively small, with a flat nose and a prehensile tail (oddly enough, old world monkeys never managed to evolve these grasping, flexible appendages). How did Branisella and its fellow new world monkeys make it all the way from Africa to South America? Well, the stretch of Atlantic Ocean separating these two continents was about one-third shorter 40 million years ago than it is today, so its conceivable that some small old world monkeys made the trip accidentally, on floating thatches of driftwood. Fairly or unfairly, old world monkeys are often considered significant only insofar as they eventually spawned apes, and then hominids, and then humans. A good candidate for an intermediate form between old-world monkeys and old-world apes was Mesopithecus, a macaque-like primate that, like apes, foraged for leaves and fruits during the day. Another possible transitional form was Oreopithecus (called the cookie monster by paleontologists), an island-dwelling European primate that possessed a strange mix of monkey-like and ape-like characteristics but (according to most classification schemes) stopped short of being a true hominid. The Evolution of Apes and Hominids During the Miocene Epoch Heres where the story gets a bit confusing. During the Miocene epoch, from 23 to 5 million years ago, a bewildering assortment of apes and hominids inhabited the jungles of Africa and Eurasia (apes are distinguished from monkeys mostly by their lack of tails and stronger arms and shoulders, and hominids are distinguished from apes mostly by their upright postures and bigger brains). The most important non-hominid African ape was Pliopithecus, which may have been ancestral to modern gibbons; an even earlier primate, Propliopithecus, seems to have been ancestral to Pliopithecus. As their non-hominid status implies, Pliopithecus and related apes (such as Proconsul) werent directly ancestral to humans; for example, none of these primates walked on two feet. Ape (but not hominid) evolution really hit its stride during the later Miocene, with the tree-dwelling Dryopithecus, the enormous Gigantopithecus (which was about twice the size of a modern gorilla), and the nimble Sivapithecus, which is now considered to be the same genus as Ramapithecus (it turns out that smaller Ramapithecus fossils were probably Sivapithecus females!) Sivapithecus is especially important because this was one of the first apes to venture down from the trees and out onto the African grasslands, a crucial evolutionary transition that may have been spurred by climate change. Paleontologists disagree about the details, but the first true hominid appears to have been Ardipithecus, which walked (if only clumsily and occasionally) on two feet but only had a chimp-sized brain; even more tantalizingly, there doesnt seem to have been much sexual differentiation between Ardipithecus males and females, which makes this genus unnervingly similar to humans. A few million years after Ardipithecus came the first indisputable hominids: Australopithecus (represented by the famous fossil Lucy), which was only about four or five feet tall but walked on two legs and had an unusually large brain, and Paranthropus, which was once considered to be a species of Australopithecus but has since earned its own genus thanks to its unusually large, muscular head and correspondingly larger brain. Both Australopithecus and Paranthropus lived in Africa until the start of the Pleistocene epoch; paleontologists believe that a population of Australopithecus was the immediate progenitor of genus Homo, the line that eventually evolved (by the end of the Pleistocene) into our own species, Homo sapiens.

The Japanese American No-No Boys in World War II

The Japanese American No-No Boys in World War II To understand who the No-No Boys were, it’s first necessary to understand the events of World War II. The United States government’s decision to place more than 110,000 individuals of Japanese origin into internment camps without cause during the war marks one of the most disgraceful chapters in American history. President Franklin D. Roosevelt signed Executive Order 9066 on February 19, 1942, nearly three months after Japan attacked Pearl Harbor. At the time, the federal government argued that separating Japanese nationals and Japanese Americans from their homes and livelihoods was a necessity because such people posed a national security threat, as they were supposedly likely to conspire with the Japanese empire to plan additional attacks on the U.S. Today historians agree that racism and xenophobia against people of Japanese ancestry following the Pearl Harbor attack prompted the executive order. After all, the United States was also at odds with Germany and Italy during World War II, but the federal government did not order mass internment of Americans of German and Italian origin. Unfortunately, the federal government’s egregious actions did not end with the forced evacuation of Japanese Americans. After depriving these Americans of their civil rights, the government then asked them to fight for the country. While some agreed in hopes of proving their loyalty to the U.S., others refused. They were known as No-No Boys. Vilified at the time for their decision, today No-No Boys are largely viewed as heroes for standing up to a government that deprived them of their freedom. A Survey Tests Loyalty The No-No Boys received their name by answering no to two questions on a survey given to Japanese Americans forced into concentration camps. Question #27 asked: â€Å"Are you willing to serve in the armed forces of the United States on combat duty, wherever ordered?† Question #28 asked: â€Å"Will you swear unqualified allegiances to the United States of America and faithfully defend the United States from any or all attack by foreign or domestic forces, and forswear any form of allegiance or obedience to the Japanese emperor, or other foreign government, power or organization?† Outraged that the U.S. government demanded that they vow loyalty to the country after flagrantly violating their civil liberties, some Japanese Americans refused to enlist in the armed forces. Frank Emi, an internee at the Heart Mountain camp in Wyoming, was one such young man. Angered that his rights had been trampled on, Emi and a half-dozen other Heart Mountain internees formed the Fair Play Committee (FPC) after receiving draft notices. The FPC declared in March 1944: â€Å"We, the members of the FPC, are not afraid to go to war. We are not afraid to risk our lives for our country. We would gladly sacrifice our lives to protect and uphold the principles and ideals of our country as set forth in the Constitution and the Bill of Rights, for on its inviolability depends the freedom, liberty, justice, and protection of all people, including Japanese Americans and all other minority groups. But have we been given such freedom, such liberty, such justice, such protection? NO!† Punished for Standing Up For refusing to serve, Emi, his fellow FPC participants, and more than 300 internees at 10 camps were prosecuted. Emi served 18 months in a federal penitentiary in Kansas. The bulk of No-No Boys faced three-year sentences in a federal penitentiary. In addition to felony convictions, internees who refused to serve in the military faced a backlash in Japanese American communities. For example, leaders of the Japanese American Citizens League characterized draft resisters as disloyal cowards and blamed them for giving the American public the idea that Japanese Americans were unpatriotic. For resisters such as Gene Akutsu, the backlash took a tragic personal toll. While he only answered no to Question #27- that he would not serve in the U.S. armed forces on combat duty wherever ordered- he ultimately ignored the draft noticed received, resulting in him serving more than three years in a federal prison in Washington state. He left prison in 1946, but that wasn’t soon enough for his mother. The Japanese American community ostracized her- even telling her not to show up at church- because Akutsu and another son dared defy the federal government. â€Å"One day it all got to her and she took her life,† Akutsu told American Public Media (APM) in 2008. â€Å"When my mother passed away, I refer to that as a wartime casualty.â€Å" President Harry Truman pardoned all of the wartime draft resisters in December 1947. As a result, the criminal records of the young Japanese American men who refused to serve in the military were cleared. Akutsu told APM he wished his mother had been around to hear Truman’s decision. â€Å"If she had only lived one more year longer, we would have had a clearance from the president saying that we are all okay and you have all your citizenship back,† he explained. â€Å"That’s all she was living for.† The Legacy of the No-No Boys The 1957 novel No-No Boy by John Okada captures how Japanese American draft-resisters suffered for their defiance. Although Okada himself actually answered yes to both queries on the loyalty questionnaire, enlisting in the Air Force during World War II, he spoke with a No-No Boy named Hajime Akutsu after completing his military service and was moved enough by Akutsu’s experiences to tell his story.​ The book has immortalized the emotional turmoil that No-No Boys endured for making a decision that is now largely viewed as heroic. The shift in how No-No Boys are perceived is in part due to the federal government’s acknowledgment in 1988 that it had wronged Japanese Americans by interning them without cause. Twelve years later, the JACL apologized for widely vilifying draft resisters. In November 2015, the musical Allegiance, which chronicles a No-No Boy, debuted on Broadway.