evolution (4)

Elephants, Mice, and Clocks...


Topics: Biology, DNA, Evolution, Research

In her laboratory in Barcelona, Spain, Miki Ebisuya has built a clock without cogs, springs, or numbers. This clock doesn’t tick. It is made of genes and proteins, and it keeps time in a layer of cells that Ebisuya’s team has grown in its lab. This biological clock is tiny, but it could help to explain some of the most conspicuous differences between animal species.

Animal cells bustle with activity, and the pace varies between species. In all observed instances, mouse cells run faster than human cells, which tick faster than whale cells. These differences affect how big an animal gets, how its parts are arranged, and perhaps even how long it will live. But biologists have long wondered what cellular timekeepers control these speeds, and why they vary.

A wave of research is starting to yield answers for one of the many clocks that control the workings of cells. There is a clock in early embryos that beats out a regular rhythm by activating and deactivating genes. This ‘segmentation clock’ creates repeating body segments such as the vertebrae in our spines. This is the timepiece that Ebisuya has made in her lab.

“I’m interested in biological time,” says Ebisuya, a developmental biologist at the European Molecular Biology Laboratory Barcelona. “But lifespan or gestation period, they are too long for me to study.” The swift speed of the segmentation clock makes it an ideal model system, she says.

These cellular clocks help explain why elephants are bigger than mice, Michael Marshall, Nature

Read more…

Habitable Epoch...


Artist's conception of GN-z11, the earliest known galaxy in the universe. Credit: Pablo Carlos Budassi Wikimedia (CC BY-SA 4.0)

Topics: Astrobiology, Evolution, Existentialism, Exoplanets

About 15 million years after the big bang, the entire universe had cooled to the point where the electromagnetic radiation left over from its hot beginning was at about room temperature. In a 2013 paper, I labeled this phase as the “habitable epoch of the early universe.” If we had lived at that time, we wouldn’t have needed the sun to keep us warm; that cosmic radiation background would have sufficed.

Did life start that early? Probably not. The hot, dense conditions in the first 20 minutes after the big bang produced only hydrogen and helium along with a tiny trace of lithium (one in 10 billion atoms) and a negligible abundance of heavier elements. But life as we know it requires water and organic compounds, whose existence had to wait until the first stars fused hydrogen and helium into oxygen and carbon in their interiors about 50 million years later. The initial bottleneck for life was not a suitable temperature, as it is today, but rather the production of the essential elements.

Given the limited initial supply of heavy elements, how early did life actually start? Most stars in the universe formed billions of years before the sun. Based on the cosmic star formation history, I showed in collaboration with Rafael Batista and David Sloan that life near sunlike stars most likely began over the most recent few billion years in cosmic history. In the future, however, it might continue to emerge on planets orbiting dwarf stars, like our nearest neighbor, Proxima Centauri, which will endure hundreds of times longer than the sun. Ultimately, it would be desirable for humanity to relocate to a habitable planet around a dwarf star like Proxima Centauri b, where it could keep itself warm near a natural nuclear furnace for up to 10 trillion years into the future (stars are merely fusion reactors confined by gravity, with the benefit of being more stable and durable than the magnetically confined versions that we produce in our laboratories).

When Did Life First Emerge in the Universe? Avi Loeb, Scientific American

Read more…

Lingua Astra...

Image Source: What a generational spaceship would actually look like, Rachel Feltman, Popular Science


Topics: Evolution, Interstellar Travel, Science Fiction, Spaceflight

Mrs. Flynt played "telephone" with us, simply lining up the entire fifth grade class in one line, arranged with chairs to accent the exercise. She showed a note to the student at the beginning of the line. She then whispered the contents of the note to the student to her right. I heard it from my neighbor, and whispered it in kind. It followed down line until it got to the last: the note's contents had completely changed from the first student to the twentieth.

I do not recall the original contents of the note, but the exercise has been repeated here on Earth without the need for fusion reactors, rotating habitats to induce artificial gravity, space lasers or Klingons. Culture on a generation starship would change from its origin planet. A society would emerge diametrically different than its original, hopefully far better than our current one, inculcating survival principles that would allow it to finish the journey to its destination, and thrive once there.

In science fiction, there’s something called a generation ship: a spacecraft that ferries humankind on a multiple-generation-long journey to brand new star systems or even galaxies.

The idea has also been touted here in the real world by those hell-bent on traversing the stars. But there’s a major problem with the concept, and we’re not talking about the countless generations doomed to be born and die for the sake of a mission they never agreed to — that’s a whole other thing. Rather, Universe Today points out that, if past is prelude, the language spoken on the ship would eventually evolve to the point that it seems incoherent back on Earth.

On an Interstellar Flight, Language Itself Would Evolve, Dan Robitzski, Futurism

Read more…

Distant Cousins...

Callao Cave, Luzon Island, The Philippines

Image credits:
Callao Cave Archaeology Project


Topics: Biology, DNA, Evolution, History, Research

(Inside Science) -- In a jungle cave in the Philippines, scientists have discovered fossils of what may be a new human species they call Homo luzonensis. The newfound teeth and bones combine primitive and modern traits in a way never previously seen together in one species, and suggest much remains to be discovered about human evolution outside Africa.
Image Source: Homo luzonensis

Although modern humans, Homo sapiens, are now the only surviving branch of the genus Homo, other species of humans once roamed across Earth. For example, previous research suggested Homo erectus, the most likely ancestor of modern humans, made its way out of Africa by at least 1.8 million years ago. In contrast, modern humans may have only begun dispersing from Africa roughly 200,000 years ago.

Fifteen years ago, scientists revealed an unusual extinct human species from the Indonesian island of Flores -- Homo floresiensis, often called "the hobbit" due to its diminutive size, which lived on Earth during the same time as modern humans. This finding hinted that other hominins -- any relatives of modern humans dating from after our ancestors split from those of chimpanzees -- might await discovery in Southeast Asia.

Researchers Find a New Ancient Human Species in the Philippines
Charles Q. Choi, Live Science

Read more…