Adapted from On the Origin of Species by Charles Darwin (1859)

The many slight differences which appear in the offspring from the same parents, or which it may be presumed have thus arisen, from being observed in the individuals of the same species inhabiting the same confined locality, may be called individual differences. No one supposes that all the individuals of the same species are cast in the same actual mold. These individual differences are of the highest importance for us, for they are often inherited, as must be familiar to every one; and they thus afford materials for natural selection to act on and accumulate, in the same manner as man accumulates in any given direction individual differences in his domesticated productions. These individual differences generally affect what naturalists consider unimportant parts; but I could show, by a long catalogue of facts, that parts which must be called important, whether viewed under a physiological or classificatory point of view, sometimes vary in the individuals of the same species. I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability, even in important parts of structure, which he could collect on good authority, as I have collected, during a course of years. It should be remembered that systematists are far from being pleased at finding variability in important characters, and that there are not many men who will laboriously examine internal and important organs, and compare them in many specimens of the same species. It would never have been expected that the branching of the main nerves close to the great central ganglion of an insect would have been variable in the same species; it might have been thought that changes of this nature could have been effected only by slow degrees; yet Sir J. Lubbock has shown a degree of variability in these main nerves in Coccus, which may almost be compared to the irregular branching of the stem of a tree. This philosophical naturalist, I may add, has also shown that the muscles in the larvæ of certain insects are far from uniform. Authors sometimes argue in a circle when they state that important organs never vary; for these same authors practically rank those parts as important (as some few naturalists have honestly confessed) which do not vary; and, under this point of view, no instance will ever be found of an important part varying; but under any other point of view many instances assuredly can be given.

Which of the following statements best summarizes the author's main idea in the passage?

"Evolution" by William Floyd (2015)

The term “human evolution” brings to mind one long smooth transition, with the human race having gone neatly from Homo habilis to Homo erectus to Homo neanderthalis and on through to the present day Homo sapiens. Lining up all of the ancestors of modern humans in front of the outline of Homo sapiens can be a convenient teaching tool in elementary and middle school classrooms, but it greatly distorts the actual course of human evolution. One human species did not simply pick up the baton of the evolutionary relay from a dying ancestor, becoming the only true hominid walking the earth. Our evolutionary ancestors were actually competing with one another for their survival, coexisting warily throughout a relatively recent period of the earth’s history.

Neanderthal has become an insult to be hurled toward a crude or unsophisticated person, but the actual Neanderthals were relatively sophisticated. Homo neanderthalis was notably larger than Homo sapiens, hunted a wide variety of animals, and spread throughout harsher climates than their hominid relatives. In fact, in many parts of modern day Europe, the remarkable dominance of Homo neanderthalis in the archaeological record shows they were the main force in Europe for tens of thousands of years. More notably, for the 5,000 years that Neanderthals shared Europe with Homo sapiens, Neanderthals were the larger presence across the continent with more tools, homesites, and burials of Neanderthals existing from the short period. There is essentially no evidence that what we think of as the “modern human” was the most perfectly adapted hominid to the world of 40,000 years ago.

The Homo sapiens, of course, eventually won out, although scientists disagree about what made the Neanderthals become permanently etched in history rather than the present. For a long time, the popular opinion was that bloody conflict between humans and Neanderthals was in the end decisively won by humans, resulting in the permanent extinction of Neanderthals from the earth. However, recent studies of Neanderthal DNA extracted from very old remains have delivered some results which shatter a notion of modern humans having demolished any trace of Neanderthals. Actually, modern humans have a significant trace of Neanderthals living within them, as a large share of the human genome contains remarkable similarities to Neanderthal DNA. Quite likely, Homo sapiens did not take over from Homo neanderthalis as the chief hominid on the planet, but in fact coexisted to the point of absorbing Neanderthals into human society and DNA.

Which of the following statements best summarizes the author's main idea in the passage?

"Darwin and Wallace" (2016)

Alfred Russel Wallace developed what he termed “the tendency of varieties to depart from the original type” while on an extended research trip in Borneo. During earlier research in the Amazon basin, Wallace had observed that certain, highly similar species were often separated by a small distance, but some type of significant geographical barrier. Although he was halfway around the world, Wallace was keeping in touch with fellow scientists in his native Britain, including Charles Darwin, who was most notable at that time for a large book on barnacles and his trip around the world on the HMS Beagle over a decade and a half earlier.

When Wallace sent Darwin a letter in February of 1858, Wallace’s intention was merely to ask if his findings in Malaysia were consistent with Darwin’s private theorizing about the development of species. Darwin received the letter in June, and was astonished at what he read from Wallace. He fired off a letter to Charles Lyell, head of the prestigious scientific organization the Linnean Society. Lyell had previously expressed concern that Darwin’s long gestating theory of natural selection would be preempted by another researcher, expressing a strong likelihood it would be Wallace.

The custom among scientists at the time called for the first person to publish a theory to be given credit for it. Wallace was well on his way to publishing his own work, largely in the form of the letter he had sent Darwin. Lyell, who had been hearing about Darwin’s theory for fifteen years, believed that both men should receive some credit. With his position of authority at the Linnean Society, Lyell arranged to have a joint paper read at the last meeting before their summer break in 1858, which took place on the first of July. The meeting was relatively well attended for the time, with over thirty people in the audience, including two foreigners. The vast majority of them were there to hear a eulogy for Robert Brown, the Scottish botanist and former president of the Society, who had passed away in early June.

Neither Alfred Russell Wallace nor Charles Darwin were present at the meeting. Wallace was still in Southeast Asia, totally unaware that the joint paper was being presented, only being informed by a letter after the meeting. Darwin was in his native Kent, far away from London, burying his recently deceased baby son, Charles Waring Darwin, who had succumbed to scarlet fever just three days previously. Darwin gave Lyell and fellow scientist Robert Hooker Wallace’s letter, a letter he had written to the American researcher Asa Gray, and an essay he had written in 1844. He then told Lyell and Hooker that he was unable to attend.

Little was made of the joint reading. Only a few small reviews were made, none of which either greatly lauded or fiercely criticized the theory of natural selection. After this, Darwin left his home with his family, seeking to get away from the disease that killed his youngest child, and began a large book on the theory. Wallace kept traveling across the Malay Archipelago, finding new evidence for the theory everywhere he went.

Charles Darwin’s name would become indelibly linked with natural selection; in particular, its subsequent overarching idea of the evolution of human beings due to the big book he was writing, On the Origin of Species. Its publication in 1859 would revolutionize how scientists thought about natural history, biology, and even science’s relation to religion. Darwin would often retreat from public scrutiny and engagement. In his stead, it was often Alfred Russell Wallace, who had returned to England in 1862, defending what became known as “Darwin’s theory.” Wallace’s significant contribution to natural selection was recognized by scientists, but rarely by the public. Nonetheless, from prompting the initial publication of the idea to staunchly fighting for it, Alfred Russell Wallace was key to the development of evolution.

Which of the following statements best summarizes the main idea of the passage?