# Where do "primative" people get their diverse intestinal bacteria from?

**URL:** <https://boards.straightdope.com/t/where-do-primative-people-get-their-diverse-intestinal-bacteria-from/735708>\
**Category:** Factual Questions\
**Created:** [October 25, 2015, 10:42am UTC](https://boards.straightdope.com/t/where-do-primative-people-get-their-diverse-intestinal-bacteria-from/735708 "2015-10-25T10:42:04Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Enilno](https://avatars.discourse-cdn.com/v4/letter/e/58f4c7/32.png) [@Enilno](https://boards.straightdope.com/u/Enilno)\
**Post date:** [October 27, 2015, 8:11pm UTC](https://boards.straightdope.com/t/where-do-primative-people-get-their-diverse-intestinal-bacteria-from/735708/21 "2015-10-27T20:11:48Z")

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> [@grude](#):
>
> Interesting, I wonder how they get to the fetus. That cite is not online and the paper’s title is vague.
> 
> I guess my real question is can I only get these diverse bacteria from people have them, or enviromentally?

Here’s a review on [Cesarean and Vaginal births](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3110651/).

> [@](#):
>
> While the paradigm has been that babies’ intestines are sterile until birth, recent work found a microbial community already dwelling in the meconium of some babies born prematurely.18 It has also been shown that amniotic fluid of mothers with preterm labor contains a large and diverse spectrum of bacterial rDNA. 20

There’s a evidence that being inoculated with the mother’s intestinal flora affects the health of the infant. In Cesarean births, the infant is mostly inoculated with environmental bacteria instead, causing potential problems later in life.

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**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\
**Post date:** [October 27, 2015, 8:27pm UTC](https://boards.straightdope.com/t/where-do-primative-people-get-their-diverse-intestinal-bacteria-from/735708/22 "2015-10-27T20:27:10Z")

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As I understand it, it’s not an issue of exposure to the bacteria - they’re everywhere. Even antibiotics only cause a temporary imbalance.

The issue in diversity and type of gut flora is mostly what you feed them. Ancient hunter-gatherers ate a very wide variety of foods, and they ate different foods in different seasons. Very few people are still eating acorns, dandelion greens, fern shoots and insect grubs. Most of are eating some combination of only about a dozen major ingredients. On top of that, we’ve largely removed seasonality: only in modern humans is it possible to eat strawberries every day.

A less varied diet supports a less varied gut flora. The ones that like the food you eat will outcompete the ones that don’t like it. If you ate a little bit of everything, then each strain of gut flora would find something like they like and they would maintain a different population balance.

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