2016 Edited to Add: When I first began writing here I generated a searchable database for references and I have since done away with that option. This entire series remains to be edited to include the full references within each piece. As time allows, this series will be edited to include complete references at the end of each part in the series.
In writing this, it has ended up as a multi-post production. So this is the first in a nine part series on the topic of FAT.
Imagine if we felt what we currently feel about fat towards our bones or muscles?
Well, we’d be busily encouraging surgeries to hack away pieces of our bones, and we’d be sucking out muscle tissue like there was no tomorrow as well.
Fat is doing a lot more than just storing energy and insulating us. It also appears to be a complex endocrine organ in our bodies. It is critical for our health and survival to have adequate fat stores.
For many on the eating disorder spectrum, fear of fat is a common facet of how the condition is expressed (at least in our modern world).
Some of you may find this series generates anxiety, but I am hoping that by learning FAT is not the enemy, it will help in your efforts to recover overall.
Can you have too much fat? Yes, but it takes going up to triple digit body mass index numbers before excess adiposity (fat tissue stores) could unequivocally be called a disease state. I’ll get into details on that concept as the series continues. And it's also not a state for which there is a "cure."
Our Aquatic Ancestors?
I am going to start at a possible beginning: did our pre-human ancestors live exclusively on the savannah in Africa, or is it more complex than we have imagined? Ah, the controversial theories – always fun to wade into these topics!
Elaine Morgan (Elaine Morgan TEDTalk) is a writer. She became frustrated that the ape-in-the-savannah theory of our evolution suggested that we lost our hair because we had to sweat while chasing down our food. But what of the females who were tending children and not running around all over the savannah? Morgan was frustrated with the male-centricity of evolutionary theories.
She came across the work of Alister Hardy, a marine biologist, who theorized that perhaps we evolved from aquatic apes. Morgan subsequently wrote a book: The Descent of Woman. The Aquatic Ape Hypothesis (known as AAH) generates much derision in academic communities, not the least of which is likely due to Morgan not being academically credentialed (she is a writer by trade).
Alister Hardy, suitably academically credentialed, originally contemplated an aquatic origin for humans based on the observation that the subcutaneous fat we have mimics blubber deposits in aquatic mammals. He began writing on the subject in the 1960s. Hardy also pioneered the biological approach to the existence of religion within human cultures. Pascal Boyer, Religion Explained: The Evolutionary Origins of Religious Thought, has taken up that torch with his very dense yet excellent book on the topic.
I am not adverse to the concept of an aquatic influence on the development of the human species. It’s not called the Blue Planet because of our skies. We were navigating waters long before we likely invented the wheel. I am not exactly sure why so many academics are hunkered down on a “savannah only” approach to our species’ development, but I’m confident that if they come across this post they’ll be sure to let me know.
“New evidence even raises the possibility that our modern human ancestors may have journeyed by raft or simple boat out of Africa 60,000 to 70,000 years ago, crossing the mouth of the Red Sea. “If they could travel from Southeast Asia to Australia 50,000 years ago, the question now is, how much farther back in time could they have been doing it?” Bailey asks. “Why not the Red Sea?”[H. Pringle, Discovery Magazine, May 2008]
Rather myopically, archaeologists have assumed we were landlubbers because there were no archeological sites suggesting otherwise. As the Discovery Magazine article suggests, it is likely because most of those sites are under about 400 feet of water now, thanks to ice sheets lowering overall ocean levels back in the day.
I am also not keen on www.aquaticape.org, the go-to site for debunking the AAH. Credentialed scientists are more than willing to refer anyone interested in considering the hypothesis to the material amassed on this site, which suggests they have not spent much time there and are dismissing it out of hand.
I have no issues with the fact that Jim Moore, a layperson, authors the site, rather that his style lacks a level of scientific objectivity. Basically I find his derision too distracting. He could learn a thing or to from Skeptical Inquirer.
In any case, we won’t get too bogged down in the theory, suffice to say that there may have been many environmental pressures that explain marked physiological and functional differences found in modern humans when compared to the great apes living today.
Our hairlessness, breath control, bradycardia, lacrimal secretions (off topic: smelling women’s tears changes men’s arousal levels), bi-pedalism, kidney morphology [M.F. Williams, 2006], paranasal sinuses and pathological conditions of the external ear canal [P.H. Rhys-Evans, 1992] may have been evolutionarily selected in ways that the “from the savannah” hypothesis cannot adequately explain.
Happy, Chubby Brains
One thing we can likely all agree on is that modern humans are chubby relative to other primates.
“In healthy adult humans, body fat usually contributes 15-20% of overall weight. In affluent societies, body fat averages more than 20% of body weight but it is rare that adults anywhere are healthy with less than 10% body fat. However, few other land animals in the wild have more than 5% body fat.” [S.C. Cunnane, Survival of the Fattest, 2005, p. 47].
Stephen Cunnane goes on to explain that body fat is a much larger component of the body weight of healthy human babies compared to other large terrestrial mammals including all other primates. Body fatness after birth is a function of early nutrition and is one of the most important indicators of normal brain development. [ibid.]
“Unlike in other primates, evolution has invested heavily in what the human brain can eventually do in an adult but has not invested in what it can immediately do in the infant.” [S.C. Cunnane, Survival of the Fattest, 2005, p.54].
However that amazing-brain-to-be in Baby has to have a really rich and stable amount of energy coming in for it to realize its potential.
Brains like to run on glucose. But brains have a back-up plan: ketone bodies (ketones). Ketones are generated from fatty acid oxidation. Newborn brains have 5 times the ketone uptake capability compared to adults [H. Kraus et al., 2009].
Interestingly, the uptake of ketones is not equal throughout all brain structures. Brains even use lactate as an energy source as well, particularly in the perinatal period [J. Medina, 2004].
Ketones are becoming a fascinating area of study when it comes to the brain’s sources of energy. It appears there are astrocytes that produce ketones in our brains suggesting additional “on location” capabilities that may protect neurons and neuronal pathways [M. Guzmán, 2001].
Where exactly could our ancestors have gotten a reliable supply of fatty acids necessary for the production of ketones in our bodies –– production that is so critical for Baby’s brain development?