The shellfish superfood appears to have been a key player in helping humans grow big brains and break away from the hominid pack 03/01/2021
All bivalves have their charm and necessary place - ideally, on a plate with garlic, parsley, and butter - but clams, scallops, and mussels must humbly take a (proverbial) knee when compared to the exquisite and enigmatic oyster.
An astonishing amount of poetry and prose is devoted to oyster consumption, on which there can be no neutral opinion: you are either an oyster person, or you are not. Perhaps the loveliest attempt comes from French poet Léon-Paul Fargue, who describes the inscrutable taste profile of an oyster “like kissing the sea on the lips.”
As an oyster person myself, I can assure you that none of the writing in praise of the oyster has been overstated. Also, people who do not like oysters are simply incorrect (Schmidt, 2020).
However, there was a time in human history - indeed, the very start of Homo sapiens history which set the course for our evolution – when, some researchers believe, everyone was an oyster person.
Message In A Bottleneck
Roughly between 195,000 and 123,000 years ago, some of our earliest human ancestors were confronted with a climate event that changed life as they knew it. Fossil records suggest the planet entered a long glacial stage which expanded deserts, made the atmosphere cold and dry, and caused a big drop in human population.
Suddenly, Homo sapiens was an endangered species.
The climate event which proved catastrophic for many of the Homo sapiens caused an interesting phenomenon: To this day, humans "exhibit very low genetic diversity relative to many other species with much smaller population sizes and geographic ranges" (Marean, 2010).
This has led some researchers to conclude that only a very small group - perhaps as small as 100 people on the coast of South Africa - was able to survive that event, resulting in what geneticists call a “population bottleneck.” Based on fossil evidence, it appears that all of us can be traced back to that small bottleneck (Marean, 2010).
So what’s this got to do with oysters?
The Pre-Paleo Diet
The hunter-gatherer diet, also commonly referred to as the “paleo diet” in recent years, is often characterized by eating high-protein, grain-free, low-sugar foods. It tends to include more fat and organ meat than typically found in the Western diet since the onset of the agricultural revolution and later industrialized food trends (Pitt, 2016).
While still controversial among mainstream practitioners and a stark reversal from the grain-heavy food pyramid so predominant in our country, the evidence for it is no longer just anecdotal: Low-sugar diets can be a marvelous weapon against the insulin resistance and metabolic problems that plague western nations (Olivieri, 2019).
Yet focusing on what was absent from our ancestral diet is perhaps less interesting than understanding what was present...yep, you guessed it.
Oysters… in abundance.
More Gathering, Less Hunting
Professor Michael Crawford of London’s Imperial College has pointed out in numerous scientific papers, conferences, and his book on evolutionary nutrition, “The Driving Force,” that we have “incontrovertible evidence” that the rapid brain growth Homo sapiens enjoyed during this timeframe (and our dependence on DHA, one of the omega-3 fats, for brain health) was likely due to a high seafood diet - and specifically, shellfish (Crawford, 1999).
Professor Crawford has questioned the “hunter” emphasis in the hunter-gatherer diet for decades now, pointing out that even today with modern tools, hunting in the African savannah is a challenge which requires complex cognitive function (Muskiet, 2004) to say nothing of the toolmaking and butchering.
Basically, you need brains to hunt. And in the bottleneck years, we didn’t quite have the brains yet.
But we did have oysters, which early humans wielding stones and primitive tools were uniquely able to open and eat. The earliest fossilized human remains clearly indicate that shellfish was a crucial staple of the ancestral diet, along with sea-bird nestlings and eggs (Broadhurst, 2002).
Simply put, it may be that humans owe it all to oysters.
“He Was A Bold Man, Who First Ate An Oyster”
No offence to Jonathan Swift, who is credited with this statement - but in the days of coastal-dwelling hunter-gatherers, it seems clear “that in coastal-hunter gatherer cultures, women [were] responsible for collecting shellfish” [emphasis added] (Parkington, 1998).
So it was more likely than not some rather bold woman who first began to gather and depend upon oysters and other mollusks for their brain-building proteins, fats, minerals, and ease of harvest. The skill and focus of women in this area would have proven especially useful during times of decreased energy and mobility, such as pregnancy and lactation (Crawford, 1999).
The abundance of shellfish and its nutrient bounty - DHA, iodine, zinc, and iron, to name a few - along with valuable probiotics to start the foundation of a healthy microbiome (Kang, 2018) make a compelling argument for the brain benefits found in oysters since humans became human.
The World Was Our Oyster
Oysters have an impressive array of multitasking powers: whether packing a nutritional punch that rivals any superfood or dazzling tastebuds with their complex and marvelous taste profile which is firmly linked to human evolution, it is clear the dependence humans have on this incredible resource goes to our ancestral roots in a profound way.
Yet, increasingly, oysters play another role in human health: nurturing the ecosystems in the estuaries they populate.
Estuaries have declined for the past 100 years due to the early overfishing that accompanied the advent of dredge technology at the start of the nineteenth century (Miller, 1986).
Oysters As Ecosystem Engineers
Today, oysters are only now beginning to enjoy some long-overdue conservation-efforts.
Not only are oysters and other bivalves crucial for constructing underwater 3d habitats and ocean environments which support innumerable critters, they singlehandedly (well, double-bivalvedly) clean those waters as well by consuming over-abundant plankton. While clams are estimated to filter up to 24 gallons per day, an adult oyster can clean as much as 50 gallons of water per day by consuming the microscopic plankton.
Conservation paleobiologists are working to create a better understanding from fossil records how oysters can uniquely combat modern threats to aquatic health such as climate change, sediment pollution, and even rising sea-levels (Lockwood, 2019).
When you choose to eat an oyster, you are not depleting them; in fact, you are supporting all of the aquaculture and conservation efforts which benefit their species, the species dependent upon their reefs, and even the future health of the ocean (King, 2018).
In short, eating an oyster is one of the most delicious and least “shellfish” acts you can perform.
- Broadhurst CL, Wang Y, Crawford MA, Cunnane SC, Parkington JE, Schmidt WF. Brain-specific lipids from marine, lacustrine, or terrestrial food resources: potential impact on early African Homo sapiens. Comp Biochem Physiol B Biochem Mol Biol. 2002 Apr;131(4):653-73. doi: 10.1016/s1096-4959(02)00002-7. PMID: 11923081.
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