Concept explainers
The unexpected discovery that humans interbred with Neanderthals was a triumph for the experts who developed the techniques for extracting, isolating, and sequencing ancient DNA. But perhaps the most stunning revelation made possible by ancient DNA was the discovery of the Denisovans, a hominin species whose existence would still be unknown if not for analysis of its ancient DNA. The fossil fragments from which the DNA was extracted were too few, too small, and too nondescript to have even been recognized as belonging to a previously unknown species. A newfound ability to identify new extinct species on the basis of DNA alone raises the intriguing possibility of future discovery of other previously unsuspected species, hommin and otherwise.
Like Neanderthals, Denisovans left a genetic trace in modern humans. One example is the Denisovan gene variant that helps Tibetans live at high altitude. Additionally, the people native to New Guinea and other Pacific islands carry a substantial number of Demsovan sequences. Almost 5% of the genome of these people is of Demsovan origin. This finding suggests that Denisovans interbred with the ancestors of Pacific Islanders, either in mainland Asia before the islands were first cotonized by people, or later, if Denisovans were somehow able to get to multiple islands.
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Biology: Life on Earth with Physiology (11th Edition)
- Why do you think such a small portion of Neandertal or Denisovan DNA exists in the gene pool of modern humans? Why not more?arrow_forwardFill the blank New genes can arise during evolution through: (i) exonshuffling, which can alter the domain structure of proteins;(ii) duplication and divergence that generates gene families;and (iii)_______ mutations in intergenic DNA sequences.arrow_forwardA large public and private effort went into sequencing the human genome. What did this project hope to accomplish; how did emerging technology assist the project (ie recombinant DNA, super-computing, automated sequencing), was it successful and what is the usefulness of what was learned in this massive effort?arrow_forward
- "Neanderthals have revealed interesting elements of the human genome". What are those elements ?arrow_forwardIf mutations such as those of the Ubx gene can drastically change morphology in a single step, why do most evolutionary biologists maintain that modification of existingtraits and the evolution of novel characters have generally proceeded by successive small steps?arrow_forwardWhat are the answers to the following images and use evidence to support your answer?arrow_forward
- Clearly, all humans have variations in their DNA sequences. How is it possible to sequence the human genome if every individual is unique? How was the diversity of the human genome addressed?arrow_forwardSome wildlife conservation organizations claim that bioengineering and cloning can be used to save endangered species. In addition, they suggest that these technologies may be used to bring back extinct species, using DNA from preserved specimens. Discuss the implications of carrying out these procedures.arrow_forwardIn 1979, bones found outside Ekaterinburg, Russia, were shown to bethose of Tsar Nicholas and his family, who were executed in 1918 by aBolshevik firing squad in the Russian Revolution. To prove that the skeletons were those of the royalfamily, mtDNA was extracted from the bone samples, amplified byPCR, and compared with mtDNA from living relatives of the tsar’sfamily.a. Why was DNA from the mitochondria analyzed instead of nuclearDNA? What are some of the advantages of using mtDNA for this type ofstudy?b. Mitochondrial DNA from which living relatives would provide usefulinformation for verifying that the skeletons were those of the royal family?arrow_forward
- Humans and chimpanzees share about 98% of their DNA. What is DNA? What might be the role of regulatory genes in producing the anatomical differences between these two lineages? Give two examples of how the field of genetics has revolutionized biological science. What is polymerase chain reaction (PCR) and why is it important in genetics?arrow_forwardEach of the following three questions contains two lists. The first is a list of some characteristics of our own species, Homo sapiens, that distinguish it from LUCA. The second is a list of possible sequences (reading from left to right) in which these novelties were acquired by our ancestors during the course of human evolution. Choose the number of the correct sequence. If none is correct, choose "None of the above." Here is the first pair of lists: A. Bilateral symmetry B. Bony skeleton C. Mitochondria D. Notochord E. Multicellularity O D, E, B, A, C O C, E, A, D, B O E, C, A, D, B O A, E, C, D, B O None of the abovearrow_forwardEven though they have several differences, a bacterium and a human cell will both contain DNA. With respect to evolution, what does this fact suggest?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning