Archaic introgression from either known or unknown extinct hominins has been suggested in different African populations [26, 30, 33,34,35,36,37,38,39]. In our data, we confirmed previous findings [28,29,30], as the results of the D-statistics of the form D(X = African population 1, Y = African population 2; Neanderthal/Denisova; Chimpanzee) showed that Eurasian samples as well as North African individuals exhibit a significant enrichment of Neanderthal DNA (higher in East Asia than in West Eurasia or North Africa) when compared to sub-Saharan African samples (Additional file 1: Figure S8.1). Z-score values are generally lower for signatures of Denisovan introgression than for Neanderthal, meaning that a lower proportion of gene flow is observed when admixture has taken place. Asian samples were enriched in archaic DNA from Denisovans, and the European and North African samples too, but at lower levels. This is probably due to the fact that Neanderthal and Denisova are sister groups and consequently share derived alleles that might confound their admixture signals. We found no signals of Neanderthal or Denisovan introgression in the sub-Saharan individuals, which was additionally confirmed with an F4-ratio test for the Neanderthal introgression (Additional file 1: Table S8.1).
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Tested demographic models. Left figures: topology of the demographic models for ABC-DL analyses considering East Asian (EAs), European (Eu), western sub-Saharan (WAf), Mbuti Pygmy (Mbt), and Khoisan (Kho) anatomically modern humans, Altai Neanderthal (N), Neanderthal-like population (NI) with introgressed DNA present in Eurasian populations, Denisova (D), Denisovan-like population (NI) with introgressed DNA present in East Asian populations, an archaic ghost population (Xe) that has left their footprint into Denisovan genome, a putative African extinct basal branch population (XAf), and a second putative archaic ghost population Neanderthal-like (Xn). In all models, recent migrations described in the text are allowed, but not shown in the figure to ease visualization. The posterior probability obtained with our ABC-DL approach is shown for each model; right figure: fitted B model
Compelling evidence accumulates in favor of interbreeding between early hominin species being common instead of exceptional. Neanderthal and Denisovan introgression in Asia, Europe, and North Africa has been well established in previous studies [30,31,32] and confirmed in our data with a D-statistics analysis. Although the poor DNA preservation in ancient samples hinders direct analyses [69], indirect evidence increasingly supports the contribution of unknown now-extinct hominins to the African genetic pool in sub-Saharan Africa [28, 35,36,37,38,39,40,41,42], where the ancestors of modern humans coexisted during the Pleistocene with different archaic humans [41]. Our ABC-DL analysis is a new incorporation to this bulk of indicia. Indeed, it corroborates that a model in which there is no archaic introgression is extremely unlikely, as was previously observed in [38]. Applying this novel strategy that includes a trained machine learning algorithm as first step, the output of which we used in the ABC analysis, we have been able to inquire complex models circumventing the demanding computational requirements for modeling such complex scenarios.
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Just this week, Nielsen Music put some numbers on this meltdown. During the first half of 2018, sales of song downloads tanked 27.4% to 223.1 million, from 307.2 million during the same period in 2017. Separately, album downloads slipped 21.7% to 27.5 million units, down from 35.1 million previously.
I said this years ago and I will say it again. As long as digital music downloads remain profitable, then there is no reason for them to ever go away. Downloads are not a physical format that requires significant scale to keep the ecosystem afloat. The market for downloads may continue to decrease, but it will eventually stabilize. Apple may discontinue the service and they may not. It is unlikely that discontinuing downloads will drive a massive influx in Apple Music subscribers at this point in the game, so they have no real incentive to kill it off as long as it continues to turn a profit which it almost certainly will for the foreseeable future. There are other players in the field too like 7Digital, which seems to be holding their own thanks to the rise in interest for hi-res audio.
In total, they fashioned around 2,000 gene variants, each a hybrid of modern plant DNA and centuries-old sequences from the hibiscus, scurfpea, conebush, or other extinct plants. All that genetic material was manufactured in a DNA synthesizer; liquid-handling robots added the gene snippets to yeast cells, and mass-spectrometry machines analyzed the resulting terpene molecules.
The Ginkgo team is not the first to reconstruct ancestral enzymes from archived specimens in living cells. Other scientists have expressed DNA from Neanderthal remains in monkey cells to better understand hair and skin pigmentation in our long-lost hominid cousins, or put woolly mammoth genes into human cells to study how the extinct Siberian beast survived so well in the extreme cold.
According to Agapakis, the de-extincted hibiscus perfume will be available for purchase as part of an art installation going on tour around the world next year, starting in February at the Georges Pompidou Center in Paris. It will then travel to the Cooper Hewitt, in New York City, and beyond.
Extinct and Endangered Animals teaches students about what it means for an animal to be endangered or extinct. They will discover several examples of animals that fall into both categories. By the end of the lesson, they will be able to define and explain both terms.
Lesson Objectives and Overview: Extinct and Endangered Animals introduces students to the concept of how animals might die off or have died off. Students will discover the many ways in which animals have become extinct or how some are in danger of extinction. The lesson is for students in 5th grade and 6th grade.
The Extinct and Endangered lesson plan contains two pages of content. The first page and a half focuses on extinction and the animals who fall into this category. The lesson introduces the concept by asking students if they have ever seen a real-life dinosaur. The answer will, of course, be no, because there are no dinosaurs on the earth any longer. They went extinct millions of years ago.
Students will learn that, at one time, there were living, breathing dinosaurs that lived on the earth. They are all gone today because they are extinct. If something is extinct, it no longer exists anywhere in the world. This can apply to plants as well, not just animals. Scientists believe many organisms died out when a large asteroid collided with earth, causing a mass extinction. A mass extinction is an event in which many species die and become extinct over a very short period of time. Normally, extinction of any species happens over a long period of time.
Many animals are in danger of becoming extinct, mostly due to human causes. When this is the case, it means that the animal is endangered. This happens when the population of a certain animal is so low that they might die out forever. The reasons animals might enter this category is mostly the same as the reasons particular animals went extinct. There are so few remaining animals of some species that you can only find them at zoos!
The lesson ends by explaining that there are ways to help protect the environments of plants and animals so that they do not become extinct or endangered. These actions include recycling, saving energy, planting a garden, or sponsoring an endangered animal.
The practice worksheet is split into three sections. Each section contains a number of descriptions or facts along with a word bank. The first section requires students to look at 5 definitions and match them to the correct term. In the second section, students will read through 5 facts and match it to the animal it represents from the word bank. The last section requires students to read through 10 examples of how animals might go extinct. They will then mark whether the reason was due to natural causes or human interaction.
Similar to the practice worksheet, there are three sections for the homework. The first section requires students to mark 10 animals as either extinct (X) or endangered (E). The next section requires them to fill in the blanks in 5 sentences using the terms in the provided word bank. Finally, they will respond to 5 prompts based on what they learned throughout the lesson.
Human settlement into new regions is typically accompanied by waves of animal extinctions, yet we have limited understanding of how human communities perceived and responded to such ecological crises. The first megafaunal extinctions in New Zealand began just 700 years ago, in contrast to the deep time of continental extinctions. Consequently, indigenous Māori oral tradition includes ancestral sayings that explicitly refer to extinct species. Our linguistic analysis of these sayings shows a strong bias towards critical food species such as moa, and emphasizes that Māori closely observed the fauna and environment. Temporal changes in form and content demonstrate that Māori recognized the loss of important animal resources, and that this loss reverberated culturally centuries later. The data provide evidence that extinction of keystone fauna was important for shaping ecological and social thought in Māori society, and suggest a similar role in other early societies that lived through megafaunal extinction events.
In common with other Pacific island environments, the arrival of humans in New Zealand resulted in high rates of extinction among its predominantly avian fauna (Duncan et al. 2002; Bromham et al. 2012). The species most affected were those especially vulnerable to human hunters, including the group of large, flightless birds known as moa [Aves: Dinornithiformes] (Holdaway 1989; Worthy 1997; Cassey 2001). Detailed reconstruction of Holocene bird fauna indicates that approximately 28 land bird species became extinct on the two main islands of New Zealand in the 500 years between initial settlement by Māori (c. AD 1280) and first European contact (AD 1769) (Worthy and Holdaway 2002; Tennyson 2006; Wood 2013). Berkes (2008) argues that ecological crises trigger learning in human communities, which in turn shapes subsequent resource management practices. However, few studies have explored the development of conservation learning in response to ecological crises, and despite the rapid loss of major avian megafauna in New Zealand less than 700 years ago (Holdaway and Jacomb 2000; Tennyson 2006; Allentoft et al. 2014; Perry et al. 2014) how this ecological change affected cultural learning remains essentially unknown. 2ff7e9595c
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