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Jovialis
11-06-18, 23:00
While humans and other species share some of the same genetic information, new research found that humans are unique among mammals when it comes to the types and diversity of microorganisms on our skin. This difference could have implications for our health and immune systems.

"We were quite surprised when we saw just how distinct we humans are from almost all other mammals, at least in terms of the skin microbes that we can collect with a swab," said Josh Neufeld, a professor of biology at the University of Waterloo and senior author of the study.

A team made up of researchers from the University of Waterloo and the University of Guelph conducted the most comprehensive survey of mammals to date and found that human microbiome—the collection of microorganisms such as bacteria, fungi, and viruses that naturally occur on our skin—contains significantly less diversity than that of other mammals.

"The first line that gets hit by modern hygienic practices is our skin," said Ashley Ross, a co-author of the study and a graduate student at Waterloo at the time of the research. "Our skin is the largest organ of the body and the main barrier to the external environment."

Living in homes, bathing and wearing clothing may all have contributed to the unique makeup of microbial communities on human skin. Habitat was another important factor linked to the skin microbes on mammals that were sampled for this study.

Despite these important influences on mammalian skin microbial communities, the study found evidence that microbial communities on mammalian skin may have changed over time with their hosts, a phenomenon called phylosymbiosis.

"We were able to measure phylosymbiosis between some of the mammalian classes and the corresponding communities on their skin," said Kirsten Müller, a biology professor at Waterloo and co-author of this study. "It's exciting that we can still see this signal despite the contribution of habitat to the skin microbial community."

The team, which also included J. Scott Weese, a professor at Guelph, plans to further examine whether co-evolution has taken place between skin microbial communities and their hosts, which is one mechanism that may account for their observations of phylosymbiosis.

The study appears this week in the Proceedings of the National Academy of Sciences and received funding from the Natural Sciences and Engineering Research Council of Canada and the Canadian Institutes for Health Research funded the project.

Read more at: https://phys.org/news/2018-06-key-difference-humans-mammals-skin.html#jCp



Comprehensive skin microbiome analysis reveals the uniqueness of human skin and evidence for phylosymbiosis within the class Mammalia

Abstract

Skin is the largest organ of the body and represents the primary physical barrier between mammals and their external environment, yet the factors that govern skin microbial community composition among mammals are poorly understood. The objective of this research was to generate a skin microbiota baseline for members of the class Mammalia, testing the effects of host species, geographic location, body region, and biological sex. Skin from the back, torso, and inner thighs of 177 nonhuman mammals was sampled, representing individuals from 38 species and 10 mammalian orders. Animals were sampled from farms, zoos, households, and the wild. The DNA extracts from all skin swabs were amplified by PCR and sequenced, targeting the V3-V4 regions of bacterial and archaeal 16S rRNA genes. Previously published skin microbiome data from 20 human participants, sampled and sequenced using an identical protocol to the nonhuman mammals, were included to make this a comprehensive analysis. Human skin microbial communities were distinct and significantly less diverse than all other sampled mammalian orders. The factor most strongly associated with microbial community data for all samples was whether the host was a human. Within nonhuman samples, host taxonomic order was the most significant factor influencing skin microbiota, followed by the geographic location of the habitat. By comparing the congruence between host phylogeny and microbial community dendrograms, we observed that Artiodactyla (even-toed ungulates) and Perissodactyla (odd-toed ungulates) had significant congruence, providing evidence of phylosymbiosis between skin microbial communities and their hosts.

http://www.pnas.org/content/early/2018/06/04/1801302115

Jovialis
11-06-18, 23:09
Basically our habits, like wearing clothing, bathing with soap, and the environments we've created for ourselves have led us to have distinct skin. It has significantly reduced the microbial diversity of our epidermis.

Maciamo
12-06-18, 09:22
Basically our habits, like wearing clothing, bathing with soap, and the environments we've created for ourselves have led us to have distinct skin. It has significantly reduced the microbial diversity of our epidermis.

That's what I thought too. Additionally, we are almost the only naked mammals (along with domestic pigs, elephants and obviously marine mammals), so microbes have less surface to adhere to. I wonder if among furry mammals, clean ones like cats have less diversity of germs on them than those who like to roll themselves in mud.

bicicleur
12-06-18, 13:59
there is one feature which is not dependant on our habits :
humans are 'naked', they don't have a fur, that's why they developped a black skin with melanine, 1.2 million years ago, to prevent decomposition of folic acid