In life, nothing ever remains the same for very long. One state is continually moving into another in a ceaseless flow of energy and information. Change, in this regard, is one of the essential characteristics of life. Seasonally, we see constant environmental shifts, such as the bright, high energy states of spring and summer, flowing into the darker, lower energy states like winter and autumn. On a smaller scale, similar shifts are seen on a daily basis between daylight and night time.
Such environmental changes elicit adaptive responses in all organisms, which can be observed seasonally in deciduous plants, for example, who lose their leaves in a process is called abscission. In some cases leaf loss coincides with winter — namely in temperate or polar climates.In other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall. Abscission demonstrates a conservation of energy when resources for growth or proliferation become scarce.
Many flowerers display reliable rhythmicity during circadian shifts in a 24 hour period, whereby the petals open and proliferate when light is available, and close down when the “stress of darkness” returns:
Similarly, mammals in temperate climates display behaviours of conservation in times of scarcity via the survival mechanisms of hibernation and deep sleep.
Mammalian hibernation consists of torpor phases when metabolism is severely depressed and various metabolically expensive systems and tissues are downregulated in their function. Hibernation affects the function of the innate and the adaptive immune systems. Torpor drastically reduces numbers of all types of circulating leukocytes. In addition, other changes have been noted, such as lower complement levels, diminished response to LPS, phagocytotic capacity, cytokine production, lymphocyte proliferation, and antibody production. (This probably underpins the phenomenon of winter illness in humans and the onsets of respiratory tract infections such as common cold around seasonal shifts.)
Stress can be broadly defined as any time in which the energetic requirements of the body outweigh its ability to provide energy. It is by way of hibernation – of shutting down of expensive apparatus – that survival in times of uncertainty (scarcity stress) is possible for many creatures.
Metabolic Switches
The salmon run is the time when salmon, which have migrated from the ocean, swim to the upper reaches of rivers where they spawn on gravel beds. After spawning, all Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again. The annual run can be a major event for grizzly bears, bald eagles and sport fishermen. Most salmon species migrate during the northern hemisphere Autumn (September through November).
Salmon, like all fish, are considered to be cold blooded, as their body temperature varies with their environment. The unsaturated fat DHA tends to be found in higher concentrations in deep, cold water fish like these, probably suggesting it has roles in maintaining fluidity of membranes and allowing for light capture where it is scarce (Crawford.) Concentrations of DHA are lower in warmer bodied animals – even fish found in the Amazon have more saturated fats than unsaturated.
salmon roe has the highest concentration of DHA of all sources, suggesting the presence of the lipid at the time of spawn – going in to winter – is protective for the eggs in the freezing conditions.
Fatty acid composition of plants also appears to be determined by growth temperature, and chill-resistant plants tend to have a higher composition of unsaturated fatty acids in their membranes. (note that vegetable or seed oils kept in a refrigerator tend not to harden, wheras saturated fat such as the tropical coconut oil tend to harden at room temperature.)
The effects of the consumption of unsaturated fats on warm blooded mammals also has the effect of coupling the organism to its local environment, whereby the ingestion of food acts like information for the system. In this regard, the environmental lipids ingested by the animal may help in slowing the metabolism to prepare for hibernation.
It is well established that unsaturated fats suppress the metabolic rate, apparently creating hypothyroidism. Lab animals fed a PUFA deficient diet, (Burr and Beber 1934), displayed markedly higher metabolic rates compared with those who consumed PUFA.
PUFA deficiency is associated with increased activity of cytochrome oxidase – a fundamental mitochondrial respiratory enzyme (Kunkel and Williams 1951). The more unsaturated the oils are, the more specifically they seem to suppress tissue response to thyroid hormone, and transport of the hormone on the thyroid transport protein.
Again we see a coupling of natures energy flows when we take a 50,000 foot view, that metabolism should increase when substrate is available and abundant (spring/summer,) when fatty acids are more saturated, and a suppression of metabolism when substrate is scarce (fall/winter) and PUFA rises. PUFA really do, in thise sense, appear to be a metablic switch to “survival metabolism.” A higher metabolic rate in the face of low substrate availability (scarcity) would be disastrous for any organism as it would entail literally oxidising any resources possible – effectively metabolising oneself to death.
Lifespan Considerations
The Fountain of Youth is a spring that supposedly restores the youth of anyone who drinks or bathes in its waters. Tales of such a fountain have been recounted across the world for thousands of years, appearing in writings by Herodotus (5th century BCE), the Alexander romance (3rd century CE), and the stories of Prester John (early Crusades, 11th/12th centuries CE). Stories of similar waters were also evidently prominent among the indigenous peoples of the Caribbean during the Age of Exploration (early 16th century), who spoke of the restorative powers of the water in the mythical land of Bimini.
The legend became particularly prominent in the 16th century, and ambiguity of the concept still continues to be an obsession amongst modern day humans. There seems to be an innate attachment youthfulness as one ages. Perhaps it is the longing for the energy of youth that one seems to only see the value in once it is gone.
The underlying cause of aging remains one of the central mysteries of biology. Recent studies in several different systems suggest that not only may the rate of aging be modified by environmental and genetic factors, but also that the aging clock can be reversed, restoring characteristics of youthfulness to aged cells and tissues. Whatever the case, humans seem hellbent on finding the “sountain of youth” in pill form, or something they can purchase.
The “rate of living” hypothesis is popular amongst anti aging practitioners, some of whom subscribe to the notion that you can live fast and die young, or live slow and last a lot longer. The rate of living theory postulates that the faster an organism’s metabolism, the shorter its lifespan. The theory was originally created by Max Rubner in 1908 after his observation that larger animals outlived smaller ones, and that the larger animals had slower metabolisms.
This theory has been clearly refuted by metabolic studies that are showing the opposite can be true – that intensified mitochondrial respiration decreases cellular damage, and supports a longer life-span. For example, small dogs eat much more food in proportion to their size than big dogs do, and small dogs have a much greater life expectancy than big dogs, in some cases about twice as long (Speakman, 2003). A similar association of metabolic intensity and life-span is seen in organisms as different from one another as are bacteria and mammals.
Bats, Birds and Tortoises all have extremely long lifespans when adjusted for body mass. Bats and birds display an incredibly high metabolic rate, whilst tortoises have some of the lowest metabolic rates. Tortoises are simple organisms, who, literally and figuratively, lead a sheltered life, moving around slowly and seemingly not being exposed to many stressors.
Conversely, birds and bats with their incredibly high metabolic rate, have the constant need for food, entailing moving about the environment and exposing themselves to stressors such as predators, environmental toxins, as well as constant energy expenditure in doing so. It seems to handle a barrage of stressors, one requires energy.
In a clinical sense, the rate of living theory is oversimplified. Cell turnover needs to be qualified according to the context. Trying to keep ubiquitination and apoptosis low is not a winning strategy for many cells, and the conditions for the cells that should not turnover, like cardiac and brain tissue, require a high metabolism (brain tissue metabolism can be definition never be low, and even in prolonged fasting, there are huge adaptations to maintain the high energy state of the brain.)
On the other hand, if skin cells and intestinal cells are not turning over every 1-3 days, you are in for big trouble. Even peripheral nervous system tissue is probably something that we want to be able to turnover at appropriate intervals. This applies to everything from wound healing to movement quality to gut functions (the gut is heavily innervated, and needs to modify those networks accordingly). The collagen matrix and connective tissues that give the body its structure (and function!) need to be re-built on a daily basis, lest major degradation in movement occurs. Even the liver needs to turnover all it’s cells every few months.
We can then see how clinically, an attachment to the rate of living theory (or an inability to see things from a broader, energetic perspective) may explain the reason why things like omega 3 oils are routinely prescribed for inflammatory conditions. Often, patients seem to have good (short term) results (due to immune suppression,) but might this strategy be creating down-regulation of other systems to a “hibernation state” whilst the organism is still stuck in the crossfire of modern life stress?
Having high PUFA in blood and tissue is a great way to become insulin resistant, suppress hormone production, suppress immune function, slow down cell turnover, and drastically reduce metabolic rate and nutrient needs (just to name a few effects). This is a survival advantage for the many animals who rely on such adaptations to go through hibernating periods. The same mechanics applied (though to a lesser degree) to humans in pre-electric times to help them get through low light environments. It could certainly be used to slow down a body that is spiralling out of control, but should these things be implemented as an anti-aging strategy, as is so often touted? A recent course i attended gave a “basic anti aging program” for an otherwise healthy adult, that included 6-8g of fish oil a day!
With PUFA depletion, hormone production and sensitivity of all forms increases, cell turnover increases, nutrient needs increase, and adaptability to various stressors increases.
Guenter Albretch-Bueller’s cell intelligence and ‘Anarchy of the Genome’ works show that metabolism is what cells use to generate the light signals they use to communicate with each other. This means high metabolism is the “adaptive state” whereby groups of cells relay local and global environmental information to each other, and select (and modify) the genes needed to deal with that environment.