Ever wonder how in the world flamingoes grow into pink adults from white chicks? Why your grandparents buy bags of lime to grow their signature pink hydrangeas? Why are most calico cats female? Why do populations exposed to famine show worsened health outcomes, generations later?
All these questions lead back to one answer: epigenetics. Nature is only mystifying until you embrace scientific curiosity, which is when the façade starts to fall.
The prefix “epi-” comes from Greek meaning “upon, over.” The word “genetics” is based in “genesis” from the Latin for “generation, creation.” Put them together, and you get epigenetics, the study of “how our environment influences our genes by changing the chemicals attached to them,” according to the Cleveland Clinic. It’s the function or expression of our (mostly) inherited, predetermined genes that change, not your genetic code itself.
Flamboyant Flamingoes
The wetland diet of adult flamingos—algae, brine fly larvae, and brine shrimp—is so rich in the red-orange beta-carotene pigment that when broken down by proteins in their stomach and absorbed by the liver, the pigments are deposited through the bloodstream in the feathers and skin.
So, the flamingo’s diet effectively “stains” their bodies pink. The fun part is that this happens even though the chicks are born gray — the phenotype their genes code for.
In the same way, every living thing—plant, animal (that includes you!), fungus, bacterium, or protist—takes part in this oversized game of rock-paper-scissors.
However, if I tried to turn myself orange by only eating carotenoid-rich carrots (their namesake), I’d probably die of malnutrition before absorbing enough pigment to succeed. But if I were a hydrangea — humor me — I could turn pink, blue, or purple if my grandmother raised or lowered my soil pH with a bit of lime (that is, if I were a mophead or lacecap)!
Lamarckism
Failure is a subject with which Jean-Baptiste Lamarck was familiar. A frenemy and predecessor of Charles Darwin, Lamarck first speculated on the idea of epigenetics with his theory of acquired inheritance. His example took a freak of nature — long giraffe necks — and attributed its evolution to a change in their DNA by generations of giraffes grazing ever higher in trees for food, stretching their necks ever longer, therefore passing on an accumulating adaptation.
However, this 19th-century naturalist pioneer theory of evolution in his 1809 Philosophie Zoologique was thrown over, fifty years later, for that of Darwin’s “descent with modification” in his 1859 On the Origin of Species. This publication, along with his and his contemporaries’ earlier writings, comprise today’s accepted natural selection theory of evolution.
But even though Lamarck was on the wrong track, he was on the right track. Although giraffes with longer necks in turn had higher fitness, passing on their genes by way of natural selection and not gene-level adaptations, he recognized the important role the environment plays.
In trying to explain natural selection, Lamarck’s mistake was focusing too much on the role of environmental pressures and not enough on that of genes. What he was getting at was epigenetic inheritance, which Darwin mistook by focusing too much on the role of genes and not enough on that of gene expression. So, neither quite hit the nail on the head but all the while contributed to the foundation on which our current knowledge is based.
That is the beauty of science: a mystery solved through time. Now, let’s take a step back to understand what Lamarck was detecting.
Why are our genes so fickle?
Science is a mystery that reveals itself upon inductive — or Holmesian — reasoning, so pull out your Conan Doyle magnifying glass. At the microscopic level, it’s clear that the human body has one main goal: efficiency, sustained by specialization and waste limitation.
The Central Dogma of biology states that genetic information flows from DNA transcribed into RNA and translated proteins. Epigenetic factors flip these proteins “on” or “off” like a light switch, which nevertheless needs a functional lightbulb, or genetic blueprint.
It would be incredibly inefficient if your muscle cells produced proteins promoting bone growth just as it would be if a gene was “on” and encoding proteins your body didn’t need. According to the National Library of Medicine, “this regulation helps ensure that each cell produces only proteins that are necessary for its function.”
Being able to turn genes “on” and “off” also gives us the wide variation in colors and patterns of Nature that provide such joy to the human eye, like the mosaic coat of calico and tortoiseshell cats.
In all female mammals with two copies of the X chromosome, only one is active or “on.,” Otherwise the amount of possibly duplicate genes could be toxic; this is X-inactivation. So, in a tortoiseshell cat carrying two X’s, each cell must make the random decision to silence one (coding for orange fur) or the other (coding for black fur).
This evolutionary advantage can come back to bite us, though, in the short- and long-term. Short? Reproductive health. Long? Generational trauma.
We say women have a “biological clock” because they’re born with an ever declining life-time supply of eggs. Men must have a stopwatch, because environmental factors like alcohol, tobacco and marijuana smoke and heat can affect the sperm count and quality of post-puberty men; that’s epigenetics!
On a larger scale, generations after the Colonial Famine in Ireland of 1845-1852 — wherein the English seized all their ancestors’ safe food save for diseased potatoes — Irish children, descendants of survivors, are predisposed to metabolic dysfunction. As health correspondent to the Irish Independent Eilish O’Regan puts it, “the ‘thrifty’ gene which helped our ancestors survive the Famine is now a liability and contributing to obesity levels.”
While we may not be able to GATTACA our designer babies yet (not that we ever should be), we can influence our own genes: right now! You don’t want a pregnant person smoking, exposing themselves and their fetus to carcinogens and possibly fatal developmental issues — like the generation of Dutch children in gestation during the Nazi-enforced Hunger Winter of 1944-1945 suffering from physical and mental health issues due to their mother’s undernutrition.
Similarly, evidence suggests that exercise can strengthen your heart while air pollution can cause asthma; the epigenome is humanity’s hidden superpower for personal and public health.
Odessa Lyon (she/her) is a junior studying biology and English, pursuing a minor in European studies.
