Are Humans Similar to Cows? Genetics, Digestion, and Implications for Diet

Similarities between people and many alternative animals are sometimes cherry-picked to argue that people are pure herbivores or omnivores. As true herbivores, cows present a mannequin in opposition to which to check human physiology and dietary wants. And evaluating our diets and bodily features to these of cows, it’s clear that they’re stricter herbivores than us.

So, the controversy over the optimum human food regimen is much less about whether or not we are able to eat animal-based meals than whether or not we must always. Moreover, evaluating ourselves to cows raises the query: are animal dairy merchandise a pure a part of the human food regimen?

Shared genes between species

All creatures, no matter their diets, share some genetic similarities. Shared genes are often related to features frequent to all animal teams. It’s not stunning, then, that we share about 80% of our genes with home cows.^[1] We’re additionally about 60% much like chickens and share 85% of our protein-encoding genes with mice.^[2]

Inside the human species, we’re all 99.9% genetically an identical to one another.^[3] Even tiny variations in genetics may end up in a variety of traits amongst people, which means that shared genes amongst animals is a perform of how nature works slightly than a sign of significant similarity.

Digestion within the ruminant abdomen

Cow stomachs vividly illustrate our variations. As ruminants, cows have a four-chamber abdomen designed to interrupt down components of vegetation that people, with our single-chamber stomachs, can’t.

Every chamber within the ruminant abdomen has a definite perform:^[4]

• The rumen is a 55-gallon chamber the place a cow’s intestine micro organism start the method of digestion.^[5]
• The reticulum pushes meals again up the esophagus to be chewed a second time earlier than digestion continues.
• The omasum filters water out of chewed plant matter from the reticulum.
• The abomasum introduces acids and enzymes to finish digestion—together with the cellulase enzyme, which is important for digesting plant fibers.

In people, plant fibers stay undigested. Once they cross into the colon, intestine microbiomes break them down to provide byproducts like nutritional vitamins and short-chain fatty acids.^[6] However since we lack the cellulase enzyme, we can not digest most of the fibers that break down simply in cows’ stomachs.

Protein and human digestion

Our stomachs are designed primarily to digest protein. When meals enters the abdomen:^[7]

• Specialised cells secrete hydrochloric acid, which unfolds proteins in a course of known as denaturation.
• Pepsin, a protein-digesting enzyme, separates denatured proteins into smaller chains of amino acids.
• Peptide chains cross into the small gut, the place pancreatic peptidase enzymes break them aside into particular person amino acids.
• Our our bodies rebuild these amino acids into proteins as wanted.

Barring any allergy symptoms or intolerances, the method works equally effectively for animal and plant proteins.

Cows, alternatively, get their protein from their ruminant microbes. These microbes can extract nitrogen from sources like grass and use it to make protein. When microbes die, additionally they get damaged down as extra protein sources.^[8] This course of permits cows to extract extra protein from a low-protein food regimen than people can.^[9]

Proteins that may’t break down within the rumen are known as rumen undegradable proteins, or bypass proteins. They cross into the abomasum and small gut for digestion and absorption. Animal-based proteins are a type of bypass protein; they’ll disrupt cows’ microbiomes, resulting in digestive misery and even loss of life.^[10]

What cows can (and may’t) educate us about human diets

Regardless of genetic similarities, cows and people have vastly totally different dietary necessities. Our digestive methods don’t totally digest among the plant matter from which cows derive most of their diet, and we are able to’t depend on our microbiomes as a principal supply of amino acids.

As a result of we are able to get these amino acids—and the opposite vitamins we’d like—from varied sources, we’ve higher dietary flexibility than cows. That is the traditional definition of an omnivore.^[11]

It bears repeating: the controversy over the optimum food regimen is much less about whether or not we are able to eat animal-based meals than whether or not we must always. Science reveals that we cannot solely survive but additionally thrive on solely plant-based diets and {that a} food regimen consisting predominantly or solely of complete plant meals tends to be your best option for long-term well being.

Given all of the variations between people and cows, you may also marvel: why will we insist on getting energy from cow’s milk and its derivatives? In new child mammalian species, the lactase enzyme is accountable for serving to break down lactose, with the expression of this enzyme declining after weaning.^[12] Primarily, weaned mammals—grownup mammals—develop out of this want to interrupt down the carbohydrate of their mom’s breast milk.

People are the main exception: via evolutionary processes that researchers are nonetheless attempting to know higher, about one-third of people have developed lactase persistence. This improvement is commonly linked to “modifications in meals manufacturing practices in the course of the Neolithic revolution,” when sure populations started domesticating animals and consuming extra of their milk. Even nonetheless, meaning the bulk is just not well-suited to eat lactose, not even the lactose of their very own species (a lot much less the lactose discovered within the milk of different species!).

References

1. “Mooove Over People, the Cow Genome Is Right here.” Science. https://www.science.org/content material/article/mooove-over-humans-cow-genome-here.
2. “People Share Virtually All of Our DNA with Cats, Cattle and Mice.” The Impartial. April 06, 2018. https://www.unbiased.co.uk/information/science/human-dna-share-cats-cattle-mice-same-genetics-code-a8292111.html.
3. Ahmed, Zeeshan, Saman Zeeshan, Dinesh Mendhe, and XinQi Dong. “Human Gene and Illness Associations for Medical‐Genomics and Precision Drugs Analysis.” Medical and Translational Drugs 10, no. 1 (Might 3, 2020): 297–318. https://doi.org/10.1002/ctm2.28.
4. Brenner, Laurie. “The Distinction Between the Human Digestive System & the Digestive System of a Cow.” Sciencing. March 02, 2019. https://sciencing.com/difference-system-digestive-system-cow-8266401.html.
5. Orr, Adam, PhD. “How Cows Eat Grass.” U.S. Meals and Drug Administration Middle for Veterinary Drugs. https://www.fda.gov/animal-veterinary/animal-health-literacy/how-cows-eat-grass.
6. Kiela, Pawel R., and Fayez Ok. Ghishan. “Physiology of Intestinal Absorption and Secretion.” Finest Follow & Analysis Medical Gastroenterology 30, no. 2 (February 16, 2016): 145–59. https://doi.org/10.1016/j.bpg.2016.02.007.
7. Knoff, Laura. “Consuming for Digestive Well being.” Essay. In Foundations of Diet, 92–97. Penngrove, CA: Bauman Faculty, 2013.
8. Moran, John. “How the Rumen Works.” Essay. In Tropical Dairy Farming: Feeding Administration for Small Holder Dairy Farmers within the Humid Tropics, 41–45. Oxford: Landlinks, 2005.
9. Cherian, Gita. “Proteins, Digestion and Absorption.” A Information to the Rules of Animal Diet. April 14, 2019. https://open.oregonstate.schooling/animalnutrition/chapter/chapter-10/.
10. Lee, April. “Do Cows Eat Meat?” Farmhouse Information. Might 02, 2022. https://farmhouseguide.com/do-cows-eat-meat/.
11. “Omnivore.” Wikipedia. October 18, 2022. https://en.wikipedia.org/wiki/Omnivore
12. Ségurel L, Bon C. On the Evolution of Lactase Persistence in People. Annu Rev Genomics Hum Genet. 2017;18:297-319. doi:10.1146/annurev-genom-091416-035340