Forget the simple out-of-Africa idea of how humans evolved. A huge array of fossils and genome studies has completely rewritten the story of how we came into being.
Shoot a rifle, and the recoil might knock you backward. Merge two black holes in a binary system, and the loss of momentum gives a similar recoil—a “kick”—to the merged black hole.
“For some binaries, the kick can reach up to 5000 kilometers a second, which is larger than the escape velocity of most galaxies,” said Vijay Varma, an astrophysicist at the California Institute of Technology and an incoming inaugural Klarman Fellow at Cornell University’s College of Arts & Sciences.
Continue reading “New method predicts which black holes escape their galaxies” »
There are endless viruses in our midst, made either of RNA or DNA viruses, which exist in much greater abundance around the planet, are capable of causing systemic diseases that are endemic, latent, and persistent—like the herpes viruses (which includes chicken pox), hepatitis B, and the papilloma viruses that cause cancer. “DNA viruses are the ones that live with us and stay with us,” Denison said. “They’re lifelong.” Retroviruses, like H.I.V., have RNA in their genomes but behave like DNA viruses in the host. RNA viruses, on the other hand, have simpler structures and mutate rapidly. “Viruses mutate quickly, and they can retain advantageous traits,” Epstein told me. “A virus that’s more promiscuous, more generalist, that can inhabit and propagate in lots of other hosts ultimately has a better chance of surviving.” They also tend to cause epidemics—such as measles, Ebola, Zika, and a raft of respiratory infections, including influenza and coronaviruses. Paul Turner, a Rachel Carson professor of ecology and evolutionary biology at Yale University, told me, “They’re the ones that surprise us the most and do the most damage.”
Scientists discovered the coronavirus family in the nineteen-fifties, while peering through early electron microscopes at samples taken from chickens suffering from infectious bronchitis. The coronavirus’s RNA, its genetic code, is swathed in three different kinds of proteins, one of which decorates the virus’s surface with mushroom-like spikes, giving the virus the eponymous appearance of a crown. Scientists found other coronaviruses that caused disease in pigs and cows, and then, in the mid-nineteen-sixties, two more that caused a common cold in people. (Later, widespread screening identified two more human coronaviruses, responsible for colds.) These four common-cold viruses might have come, long ago, from animals, but they are now entirely human viruses, responsible for fifteen to thirty per cent of the seasonal colds in a given year. We are their natural reservoir, just as bats are the natural reservoir for hundreds of other coronaviruses. But, since they did not seem to cause severe disease, they were mostly ignored. In 2003, a conference for nidovirales (the taxonomic order under which coronaviruses fall) was nearly cancelled, due to lack of interest. Then SARS emerged, leaping from bats to civets to people. The conference sold out.
SARS is closely related to the new virus we currently face. Whereas common-cold coronaviruses tend to infect only the upper respiratory tract (mainly the nose and throat), making them highly contagious, SARS primarily infects the lower respiratory system (the lungs), and therefore causes a much more lethal disease, with a fatality rate of approximately ten per cent. (MERS, which emerged in Saudi Arabia, in 2012, and was transmitted from bats to camels to people, also caused severe disease in the lower respiratory system, with a thirty-seven per cent fatality rate.) SARS-CoV-2 behaves like a monstrous mutant hybrid of all the human coronaviruses that came before it. It can infect and replicate throughout our airways. “That’s why it is so bad,” Stanley Perlman, a professor of microbiology and immunology who has been studying coronaviruses for more than three decades, told me. “It has the lower-respiratory severity of SARS and MERS coronaviruses, and the transmissibility of cold coronaviruses.”
The hydra is named after the serpent monster from Greek myth, which regrows two heads each time one is cut off. But freshwater hydras have an even more impressive regenerating ability: an entire hydra can regrow from a small piece of tissue in only a few days.
Biologists are particularly excited by this ability, since many of the networks involved in the healing process developed early in the process of evolution, meaning that they are shared among many animals, including humans.
“In other organisms, like humans, once our brain is injured, we have difficulty recovering because the brain lacks the kind of regenerative abilities we see in hydra,” said researcher Abby Primack.
Josie Golding, Ph.D., who is the epidemics lead at the Wellcome Trust, a research charity based in London, United Kingdom, did not participate in the study but comments on its significance.
She says the findings are “crucially important to bring an evidence-based view to the rumors that have been circulating about the origins of the virus (SARS-CoV-2) causing COVID-19.”
“[The authors] conclude that the virus is the product of natural evolution,” Goulding adds, “ending any speculation about deliberate genetic engineering.”
I know some have speculated that the Coronavirus was engineered:
An analysis of public genome sequence data from SARS-CoV-2 and related viruses found no evidence that the virus was made in a laboratory or otherwise engineered.
The novel SARS-CoV-2 coronavirus that emerged in the city of Wuhan, China, last year and has since caused a large scale COVID-19 epidemic and spread to more than 70 other countries is the product of natural evolution, according to findings published today in the journal Nature Medicine.
Continue reading “COVID-19 coronavirus epidemic has a natural origin” »
Stellar streams are long, thin filaments of stars orbiting galaxies, produced by the stretching action of tidal forces. For astronomers, observation of these structures could be crucial to test various galaxy formation models.
Located most likely some 420 light-years away in the Milky Way’s disk, Pisces–Eridanus (or Psc–Eri for short) is a cylindrically shaped stream of almost 1,400 identified stars distributed across about 2,300 light-years. Due to its relative proximity and population size, it is perceived as an excellent laboratory to study star formation and test theories of chemical and dynamical evolution of stellar systems.
An ancient Elpistostege fish fossil found in Miguasha, Canada has revealed new insights into how the human hand evolved from fish fins.
An international team of palaeontologists from Flinders University in Australia and Universite du Quebec a Rimouski in Canada have revealed the fish specimen, as described in the journal Nature, has yielded the missing evolutionary link in the fish to tetrapod transition, as fish began to foray in habitats such as shallow water and land during the Late Devonian period millions of years ago.
This complete 1.57 metre long fish shows the complete arm (pectoral fin) skeleton for the first time in any elpistostegalian fish. Using high energy CT-scans, the skeleton of the pectoral fin revealed the presence of a humerus (arm), radius and ulna (forearm), rows of carpus (wrist) and phalanges organized in digits (fingers).
:oooooo.
Rutgers researchers have discovered the origins of the protein structures responsible for metabolism: simple molecules that powered early life on Earth and serve as chemical signals that NASA could use to search for life on other planets.
Their study, which predicts what the earliest proteins looked like 3.5 billion to 2.5 billion years ago, is published in the journal Proceedings of the National Academy of Sciences.
Continue reading “Scientists have discovered the origins of the building blocks of life” »
The behavior of one of nature’s humblest creatures is helping astronomers probe the largest structures in the universe.
The single-cell organism, known as slime mold (Physarum polycephalum), builds complex filamentary networks in search of food, finding near-optimal pathways to connect different locations. In shaping the universe, gravity builds a vast cobweb structure of filaments tying galaxies and clusters of galaxies together along faint bridges hundreds of millions of light-years long. There is an uncanny resemblance between the two networks: one crafted by biological evolution, and the other by the primordial force of gravity.
The cosmic web is the large-scale backbone of the cosmos, consisting primarily of the mysterious substance known as dark matter and laced with gas, upon which galaxies are built. Dark matter cannot be seen, but it makes up the bulk of the universe’s material. The existence of a web-like structure to the universe was first hinted at in the 1985 Redshift Survey conducted at the Harvard-Smithsonian Center for Astrophysics. Since those studies, the grand scale of this filamentary structure has grown in subsequent sky surveys. The filaments form the boundaries between large voids in the universe.
