In 2009 a helicopter with a medical mission landed in an Amazon rainforest at an unmapped isolated village, first spotted by the Venezuelan army in 2008.

It was a community of 34 Yanomami people, untouched by the outside world. They were semi-nomadic hunter-gatherers, living as their ancestors did some 12,000 years ago.

Skin microbiome samples were taken that revealed the highest species diversity recorded in a human group. Not even an individual microbe strain dominated skin areas sampled. It was a stark contrast to the skin quality of modern humans.

It was biologically perfect skin - something progress left behind.

Figure 01: Amazon rainforest Yanomami people Shapono. A village built as a communal roundhouse. 

Briefly: The Skin Microbiome

The skin microbiome is gaining consumer interest because this vast ecosystem of microbes is identified by scientists as critical to skin function and health.

The skin microbiome is an ecosystem of helpful (commensal) microbes. It’s mainly comprised of bacteria species but also includes fungi and viruses.

This ecosystem is an integral part of our skin barrier and performs multiple roles. It crowds-out harmful (pathogens) microbes that land on the skin, maintains our skin immune defence via complex cross-talk with the host skin tissue - and much more.

What’s driving this biology into the mainstream are consumer concerns about the negative impact of modern life on their skin. Looking at levels of skin microbiome species diversity tells us about impact, as it’s a measure of skin’s ecosystem balance, robustness and health.

Heathy Diversity: Paradise Lost

The graph below compares diversity of healthy Agrarian and Western skin bacteria. It shows that a fully-urbanised human has lost some 30% of skin biodiversity compared to a near pre-urban ancestor. This loss has significant implications for skin health.

Figure 02: Extrapolated 16S rRNA sequences of skin microbiome diversity. “Agrarian” denotes ex semi-nomadic Amerindians, VE-Z, sedentary villagers with low urban and high Amazonian rainforest exposure. “Western” denotes fully-urban Americans of New York City, NY and Boulder, CO, USA.

Credit: Wallen-Russell, C.; Wallen-Russell, S. “Meta-Analysis of Skin Microbiome: New Link between Skin Microbiota Diversity and Skin Health with Proposal to Use This as a Future Mechanism to Determine Whether Cosmetic Products Damage the Skin.” Cosmetics 2017, 4, 14.

The authors of this study were unable to compare species diversity of these Yanomami people against their Agrarian and Western data, so the diversity loss of fully-urban humans compared to our pre-urban ancestors could be much higher than 30%.

Diversity: Decline Implications

Species diversity is a measure of an ecosystem’s health. The contrast between the skin microbiomes of Amerindians and North Americans highlights the profound impact of modern life on skin health, including weakened immune defences and dermatological conditions.

This disparity begs many questions, including: what’s caused this biodiversity decline, and what practical actions can I take to mitigate or reverse skin microbiome damage?