Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

When humans evolved a super-high cooling capacity + Reptile had 1st opposed thumb

#1
C C Offline
The Chillest Ape: How Humans Evolved A Super-High Cooling Capacity
https://www.pennmedicine.org/news/news-r...g-capacity

RELEASE: Humans have a uniquely high density of sweat glands embedded in their skin—10 times the density of chimpanzees and macaques. Now, researchers at Penn Medicine have discovered how this distinctive, hyper-cooling trait evolved in the human genome. In a study published today in The Proceedings of the National Academy of Sciences of the USA, researchers showed that the higher density of sweat glands in humans is due, to a great extent, to accumulated changes in a regulatory region of DNA—called an enhancer region—that drives the expression of a sweat gland-building gene, explaining why humans are the sweatiest of the Great Apes.

“This is one of the clearest examples I’ve ever seen of pinpointing the genetic basis for one of the most extreme and distinctively human evolutionary traits as a whole,” said the study’s senior author, Yana Kamberov, PhD, an assistant professor of genetics at Penn Medicine. “This kind of research is important not only because it shows how evolution actually works to produce species diversity but also because it gives us access into human biology that is often not possible to gain in other ways, essentially by learning from tweaking the biological system in a way that is actually beneficial, without breaking it.”

Scientists broadly assume that humans’ high density of sweat glands, also called eccrine glands, reflects an ancient evolutionary adaptation. This adaptation, coupled with the loss of fur in early hominins, which promoted cooling through sweat evaporation, is thought to have made it easier for them to run, hunt, and otherwise survive on the hot and relatively treeless African savannah, a markedly different habitat than the jungles occupied by other ape species.

Kamberov found in a 2015 study that the expression level of a gene called Engrailed 1—EN1 in humans—helps determine the density of eccrine glands in mice. EN1 encodes a transcription factor protein that, among many other functions, works during development to induce immature skin cells to form eccrine glands. Because of this property, Kamberov and colleagues hypothesized that perhaps one way in which humans could have built more sweat glands in their skin is to evolve genetic changes that increased the production of EN1 in the skin.

The activity of a gene is often affected by nearby regions of DNA called enhancer regions, where factors that activate the gene can bind and help drive the gene’s expression. In the study, Kamberov and her team identified an enhancer region called hECE18 that boosts the production of EN1 in skin, to induce the formation of more eccrine glands. The researchers showed that the human version of hECE18 is more active than that of ape or macaque versions, which would in turn drive higher levels of EN1 production.

Kamberov and her colleagues also teased apart the individual mutations that distinguish human hECE18, showing why some of them boost EN1 expression—and showing that rolling back those mutations to the chimp version of hECE18 brings the enhancer activity down to chimp levels.

Prior studies of evolved human-specific traits, such as language, generally have tied such traits to complex genetic changes involving multiple genes and regulatory regions. In contrast, the work from Kamberov and her team suggest that the human “high-sweat” trait evolved at least in part through repeated mutations to just one regulatory region, hECE18. This means that this single regulatory element could have repeatedly contributed to a gradual evolution of higher eccrine gland density during human evolution.

While the study is mainly a feat of basic biology that shines a light on human evolution, it also should have some long-term medical relevance, Kamberov said.

“Severe wounds or burns often destroy sweat glands in skin, and so far we don’t know how to regenerate them—but this study brings us closer to discovering how to do that,” she said. “The next step in this research would be to uncover how the multiple activity enhancing mutations in hECE18 interact with each other to increase EN1 expression and to use these biologically key mutations as starting points to figure out what DNA-binding factors actually bind at these sites. Basically, this provides us with a direct molecular inroad to discover the upstream factors that by activating EN1 expression get skin cells to start making sweat glands.”


Monkeydactyl reveals the oldest opposed thumb
https://www.birmingham.ac.uk/news/latest...ptile.aspx

RELEASE: A new 160-million-year-old arboreal pterosaur species, dubbed ‘Monkeydactyl’, has the oldest true opposed thumb - a novel structure previously not known in pterosaurs. An international team of researchers from China, Brazil, UK, Denmark and Japan have described a new Jurassic pterosaur Kunpengopterus antipollicatus, which was discovered in the Tiaojishan Formation of Liaoning, China.

It is a small-bodied darwinopteran pterosaur, with an estimated wingspan of 85 cm. Most importantly, the specimen was preserved with an opposed pollex (“thumb”) on both hands.

The species name ‘antipollicatus’ means ‘opposite thumbed’ in ancient Greek, in light of the opposed thumb of the new species. This is the first discovery of a pterosaur with an opposed thumb. It also represents the earliest record of a true opposed thumb in Earth’s history. The researchers published their today in the journal Current Biology.

A true opposed pollex is mostly present in mammals (e.g. primates) and some tree frogs, but extremely rare among extant reptiles except for chameleons. This discovery adds to the list that darwinopteran pterosaurs such as K. antipollicatus also evolved an opposed thumb.

The research team scanned the fossil of K. antipollicatus using micro-computed tomography (micro-CT), a technique making use of X-ray to image an object. By studying its forelimb morphology and musculature, they suggest that K. antipollicatus could have used its hand for grasping, which is likely an adaptation for arboreal life.

In order to test the arboreal interpretation, the team analysed K. antipollicatus and other pterosaurs using a set of anatomical characters related to arboreal adaptation. The results support K. antipollicatus as an arboreal species, but not the other pterosaurs from the same ecosystem. This suggests niche-partitioning among these pterosaurs and provides the first quantitative evidence that at least some darwinopteran pterosaurs were arboreal.

Fion Waisum Ma, co-author of the study and PhD researcher at the University of Birmingham, said: “The fingers of ‘Monkeydactyl’ are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through the rocks, create digital models and tell how the opposed thumb articulates with the other finger bones. “This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur - which wasn’t known for having an opposed thumb."

Xuanyu Zhou from China University of Geosciences who led the study commented: “Tiaojishan palaeoforest is home to many organisms, including three genera of darwinopteran pterosaurs. Our results show that K. antipollicatus has occupied a different niche from Darwinopterus and Wukongopterus, which has likely minimized competition among these pterosaurs.”

Rodrigo V. Pêgas from Federal University of ABC, in Sao Bernardo, Brazil, said: “Darwinopterans are a group of pterosaurs from the Jurassic of China and Europe, named after Darwin due to their unique transitional anatomy that has revealed how evolution affected the anatomy of pterosaurs throughout time. “On top of that, a particular darwinopteran fossil has been preserved with two associated eggs, revealing clues to pterosaur reproduction. They’ve always been considered precious fossils for these reasons and it is impressive that new darwinopteran species continue to surprise us!”
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
  Myth of "primitive communism" + Were Clovis people 1st humans in Americas after all? C C 0 59 May 1, 2022 06:52 AM
Last Post: C C



Users browsing this thread: 1 Guest(s)