Items tagged with: species
There's a new addition to the family tree: an extinct species of human that's been found in the Philippines.
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By Paul Rincon Science editor, BBC News website
Proximal foot phalanx Image copyright Florent Detroit Image caption The finger and toe bones are curved, suggesting climbing was still an important activity for this species
Thereʼs a new addition to the family tree: an extinct species of human thatʼs been found in the Philippines.
Itʼs known as Homo luzonensis, after the site of its discovery on the countryʼs largest island Luzon.
Its physical features are a mixture of those found in very ancient human ancestors and in more recent people.
That could mean primitive human relatives left Africa and made it all the way to South-East Asia, something not previously thought possible.
The find shows that human evolution in the region may have been a highly complicated affair, with three or more human species in the region at around the time our ancestors arrive.
One of these species was the diminutive "Hobbit" - Homo floresiensis - which survived on the Indonesian island of Flores until 50,000 years ago.
Prof Chris Stringer, from Londonʼs Natural History Museum, commented: "After the remarkable finds of the diminutive Homo floresiensis were published in 2004, I said that the experiment in human evolution conducted on Flores could have been repeated on many of the other islands in the region.
"That speculation has seemingly been confirmed on the island of Luzon... nearly 3,000km away."
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The new specimens from Callao Cave, in the north of Luzon, are described in the journal Nature. They have been dated to between 67,000 years and 50,000 years ago.
They consist of thirteen remains - teeth, hand and foot bones, as well as part of a femur - that belong to at least three adult and juvenile individuals. They have been recovered in excavations at the cave since 2007.
Homo luzonensis has some physical similarities to recent humans, but in other features hark back to the australopithecines, upright-walking ape-like creatures that lived in Africa between two and four million years ago, as well as very early members of the genus Homo.
The finger and toe bones are curved, suggesting climbing was still an important activity for this species. This also seems to have been the case for some australopithecines.
Image copyright Florent detroit
Image caption The teeth of Homo luzonensis are consistent with the remains being assigned to a new species
If australopithecine-like species were able to reach South-East Asia, it would change the way our ideas about who in our human family tree left Africa first.
Homo erectus has long thought to have been the first member of our direct line to leave the African homeland - around 1.9 million years ago.
And given that Luzon was only ever accessible by sea, the find raises questions about how pre-human species might have reached the island.
In addition to Homo luzonensis, island South-East Asia also appears to have been home to another human species called the Denisovans, who appear to have interbred with early modern humans (Homo sapiens) when they arrived in the region.
Image copyright Florent Detroit
Image caption Callao Cave, in the north of Luzon, is open to tourists
This evidence comes from analysis of DNA, as no known Denisovan fossils have been found in the region.
The Indonesian island of Flores was home to a species called Homo floresiensis, nicknamed The Hobbits because of their small stature. They are thought to have survived there from at least 100,000 years ago until 50,000 years ago - potentially overlapping with the arrival of modern humans.
Interestingly, scientists have also argued that Homo floresiensis shows physical features that are reminiscent of those found in australopithecines. But other researchers have argued that the Hobbits were descended from Homo erectus but that some of their anatomy reverted to a more primitive state.
In an article published in Nature, Matthew Tocheri from Lakehead University in Canada, who was not involved with the research, commented: "Explaining the many similarities that H. floresiensis and H. luzonensis share with early Homo species and australopiths as independently acquired reversals to a more ancestral-like hominin anatomy, owing to evolution in isolated island settings, seems like a stretch of coincidence too far."
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Accelerated modern human–induced species losses: Entering the sixth mass extinction
The oft-repeated claim that Earth’s biota is entering a sixth “mass extinction” depends on clearly demonstrating that current extinction rates are far above the “background” rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way.Светлана Лада wrote the following post Tue, 09 Apr 2019 18:52:27 +0300
Ученые: Земле понадобится 10 миллионов лет, чтобы восстановиться
Причина — в скорости эволюционных процессов.
Понадобится не менее 10 миллионов лет, чтобы жизнь на Земле возродилась после шестого массового вымирания, которое уже началось
Несколько лет назад международная группа биологов заявила, что сейчас на Земле действительно происходит шестое массовое вымирание животных, вызванное не природными причинами, а деятельностью человека.
Они опирались на данные по частоте исчезновения видов флоры и фауны в прошлом.
По их расчетам, в эпохи, предшествовавшие антропоцену, каждые сто лет исчезало примерно по два вида млекопитающих на каждые десять тысяч существовавших. В ХХ веке эта цифра выросла в 114 раз.
В новом исследовании ученые изучали окаменелости фораминифер — одноклеточных организмов, которые жили в древних морях. Почти все виды были уничтожены в результате падения астероида, но некоторые смогли выжить.
Выжившие фораминиферы заполнили освободившиеся экологические ниши, но это заняло около 10 млн лет.
Таким образом, сдерживающим фактором в вопросе восстановления жизни на Земле является сама эволюция, заявили ученые.
#6thMassExtinction #civilization #diversity #documents #extinction #humanism #massextinction #nature #science #species #time #timespace
Over the past 40 years, there has been a dramatic decline in fishery landings of an iconic Baltic Sea fish: the flounder. In the 1980s, the landings of the flounder fishery in the Gulf of Finland dropped by 90 per cent, a trend that was later confirmed by fishery-independent surveys.
Genetic analysis uncovers a direct descendant of two different groups of early humans.https://www.nature.com/articles/d41586-018-06004-0
Мама неандерталка, папа денисовец: первое открытие древне-человеческого гибрида
Генетический анализ раскрывает прямого потомка двух разных групп ранних людей.#dna #human #hominid #hybrid #metaprogramming #nature #past #revision #science #species