Apostrophe: an exclamatory figure of speech. It occurs when a speaker breaks off from addressing the audience (e.g. in a play) and directs speech to a third party.
I'm not into food fads. Not at all. But I am intrigued by a recent documentary I heard about fermented foods. Foods transformed by microorganisms are very common: cheese, wine, beer, yoghurt, pickles, soy sauce, etc. But in most of them, the bugs are either dead or we kill em.
Yogurt, sauerkraut, tempeh, blue cheeses, and other foods contain living microorganisms: bacteria and fungi (including yeasts).
Giving rise to the joke.
Q. What is the difference between yogurt and {country X that you wish to ridicule}?
A. Yogurt has a living culture.
And the idea is that these bugs take up residence and help make us healthy.
One of my great science heroes is microbiologist Lynn Margulis (d. 2011), one of the great scientists of the 20th Century. Margulis established that the mitochondria which live in all of our cells were once free living bacteria. She emphasised the role of symbiosis in evolution (in contradiction to the fetishisation of competition amongst male biologists). This has been one of the strongest influences on my thinking about the world: the importance of symbiosis, hybridization, communities, and cooperation. We are not only social animals, but in fact, we are colonies of cells, with many different symbionts living in our gut. A colony of colonies.
For many decades the existence of bacteria and fungi living in our gut, as symbionts, not pathogens was scarcely acknowledged. In the last ten years or so it has started to dawn on the world of biology that Margulis was on to something big. These intestinal flora are not passive hitch-hikers. They are actively involved in homoeostasis - the collection of processes by which we maintain our internal milieu at the optimum for life.
We now know, for example, that gut microbes participate in and contribute to our immune system. They are involved in processes that govern blood-sugar. And so on. Our gut is full of symbionts - a mutually beneficial association. Thousands of species of them and in vast numbers (perhaps as many as 100 of their cells for every cell in our body, though this figure has been challenged).
I think most people are probably aware that yoghurt has this reputation for repopulating the gut with healthy bacteria. But now expand that out to every food with living bugs. And keep in mind that the gut contains a community of bugs, all "communicating" and working together. Thousands of species are involved. And it seems the more the merrier.
I'm certainly not conducting a scientific experiment, but as part of an effort to eat healthily, I'm now regularly including sauerkraut in my diet and some soy-based yoghurt. The sauerkraut is a bit of an acquired taste, but tastes can be acquired with repeated exposure (like olives). And actually, sauerkraut is *very* easy to make so I might have a go at it.
The cells that make up our bodies all come from that single fertilised egg created at our conception. It divides into 2, 4, 8, 16, etc. None of our cells was ever dead and infused with life. All of our cells were always living because each cell was created by a mother cell dividing into two daughters.
The sperm and ova that became our first cell were also living cells. produced by cell division in our parents. All of our parents' cells were also always alive and multiplied by dividing.
All the cells of every animal, going back into the mists of time originating by one living cell becoming two living cells. Similarly for all plants, fungi, and bacteria too. All cells come from dividing. All cells except the original cells.
We have a pretty good idea of how such cells might have formed, but we don't know for sure. But in any case, everything alive to day, literally every living cell, was produced by cell division. Every living cell, and thus every living thing, is a direct-line descendant of those first living cells. Every living cell is directly related to every other living cell.
Along the way, some of the cells recombined to make more complex cells or formed symbiotic relationships. Combining is as important as division in evolution, though it happens less often.
The lines of living cells, going back to the original cells, are unbroken for at least 3.5 billion years, possibly longer. Each individual cell eventually dies, but the processes of life continue, without interruption. And even if humans manage to wipe themselves out, bacteria will survive literally anything we can do. Some bacteria live in boiling pools of acid, so nothing we do is going to kill them all. Life will continue on earth at least until our sun expands out to become a red giant, engulfing the earth in fire, about 5 billion years from now. But there is a good chance that by then humans will have seeded life on other planets, if only in our solar system. So in all probability, life will go on indefinitely.
The only limit is that life requires an input of energy which can be put to use. And this will have completely run out in our universe by about 10^100 (1 followed by 100 zeros) years from now. Then it's curtains for life in this universe. Until then, however, life goes on.
I just heard Carlo Rovelli explain a scenario for blackholes, let's see if I can reproduce it.
Take a supermassive star. As it reaches the point where it has fused together the last fusionable elements, it begins to cool. Since the heat generated by nuclear fusion has been the only thing preventing gravity from collapsing all the matter into the centre, it begins to collapse. Matter from the star rushes towards the centre very fast, causing an implosion. This throws most of the matter back out into space, but at the very core matter becomes super-compressed. All the protons and electrons are converted into neutrons and these are squeezed into very dense neutronium that takes up very little space.
Relativity says that above a certain mass the neutron core of the star continues to be compressed by gravity and that there is no limit to this compression. If there is enough matter to start with, the neutronium becomes so dense that nothing can reach escape velocity and it becomes a blackhole. Compression continues forever making the star effectively infinitely small with infinite density.
However, regions of infinite density are ruled out by quantum mechanics. Even a blackhole must have a finite density - the smallest possible scale is the Planck length of 10-33m, and the smallest possible volume is a Planck cubed. Rovelli suggests that a blackhole collapses down to a minimum, but finite, volume and then explodes outwards again. And this process takes about 1 millisecond.
What? If we go back to Relativity it says that the closer we are to a large mass, the slower time will go for us compared to a distance observer. This is because of the fixed speed of light. Near a large mass, space is tightly curved and distances between points are compressed, but light goes the same speed (300,000 ms-1), so in order for the speed (ms-1) to remain the same, time must slow down. If a blackhole caused infinite density, then time would have to cease. But since matter it cannot be infinitely dense, due to the limit on how small a volume of space is, time must continue to pass, however slowly. But since the time dilation occurs to everything at once, subjectively time would probably continue to pass at the same rate near the mass. It is only a distant observer who would see things slowing down.
If we were able to travel down into the heart of a blackhole as it collapsed and bounced back, it would seem to take about 1 ms to us. Subjectively, inside the blackhole time would continue pass at normal speed. But if we are looking at a blackhole collapsing from several light years away, the process would appear to take billions of years. And this is why we don't see blackholes exploding.
If blackholes do explode then we ought to be able to see it, and this is something that astronomers can look for. Perhaps such explosions would be visible to the LIGO gravity wave detector or some future detector which is more sensitive?
At the moment this is just hand-wavy stuff. Something other than a singularity must exist in a blackhole, because of quantum mechanics, but we're not sure what it is yet. This is quite a cool scenario though.
I was so taken with David Attenborough's recent documentary on the Aquatic Ape Hypothesis, The Water Side Ape that I listened to both episodes twice and took some notes.It seems the idea is now mainstream after a few decades of being marginal, thanks largely to the efforts of the late Elaine Morgan. To be clear, Morgan always maintained that this was a hypothesis and not a theory. She argued that it was up to scientists to examine the hypothesis, see what predictions it might make, and test these predictions, which is the gold standard for scientific method. Most scientists have been very reluctant to even consider the hypothesis, frequently arguing that there is "no evidence for it", which is the opposite of science.
The idea of the AAH is that at some stage in our evolution, well before modern humans emerged, we foraged main in water for all or part of the year, but also spend time on land, and presumably in trees. Spending a lot of time wading and diving in water over tens of thousands or even hundreds of thousands of years led to partial adaptations to that environment that make humans superficially unlike any other great ape, for example we are upright, bipedal, and relatively hairless (hence we are the "naked ape"), except on our heads where we grow extraordinarily long hair.
The mainstream view was that we were semi-arboreal like chimps are today, but that the climate changed and left us living on the savannah that now covers eastern, sub-Saharan Africa. Why we did not do what other species of apes did and move with the trees, is not clear. Put a chimp on the savannah and it has no food and no protection from group predators like hyenas and lions. Chimps can defend against their main predators, leopards, because they are solitary hunters who can be driven off by a concerted group effort. Not so hyenas!
According to this hypothesis, life on the savannah encouraged us to walk upright and left our hands free for other tasks, though whether this was tools, weapons, or babies is unclear. But if the chimp is badly adapted to finding a living on the savannah, make them stand upright to move about and they are suddenly visible to predators from far off and too slow to run away from most predators because four-legged gaits are must faster!
Losing our body hair is said to be an adaptation to heat loss, but we are curiously the only African animal of that area that lost our body hair. If it heat loss was the driver, then their ought to have been parallel evolution of other naked animals. But there was not, except for the hippopotamus which spends most of its time in the water!
But it has recently emerged that in fact there was no savannah where we evolved when we evolved. The area was woodland and wetlands. The savannah hypothesis idea is definitely defunct. Which leaves the field open and the aquatic ape hypothesis ought to be a contender. Some of the key points follow.
Adaptations to a Semi-Aquatic Lifestyle.
Like other aquatic mammals we are relatively hairless and have a layer of subcutaneous fat (or blubber). Land mammals don't need the buoyancy and insulation that blubber provides; and where they do need insulation, they tend to opt for fur instead. Except in the semi-aquatic hippo.
We also share a curious feature with seals that we share with no terrestrial mammal, i.e. vernix - the (water-proof) waxy coating that covers new born babies. In fact it was a prediction of the hypothesis that aquatic mammals might share this feature with us, and the discovery of vernix in seals is a confirmed prediction of the hypothesis.
The AAH argues that wading was the origin of bipedalism. Other normally quadrupedal modern apes, i.e. chimps and baboons, switch to bipedalism when wading. Land-based bipedalism would have left us with a major a disadvantage in terms of speed before we were fully adapted to running. Chimps for example are very much slower and less manoeuvrable on two legs than on four. But equally any adaptations towards bipedalism would have been a major disadvantage to arboreal life. Loosing the ability to grip with feet, for example, makes life in the trees much less viable. In other words, the early trait, which had to have lasted millennia would have not survived natural selection if we were solely land-based because disadvantages outweighed advantages. Bipedalism on land would have killed us off. Only once we were fully upright and agile could be have started running on two legs. You have to walk before you can run.
There is also good evidence for food collection from water dating well before anatomically modern humans (going back 2 million years in fact). Especially good evidence for catching and consumption of-large fresh water fish that were rich in omega 3 fatty acids and thus probably contributed to our growing brains. Add to this the recent observation of chimps using long sticks to "fish" for pond algae, also high in protein and fatty acids. These foods are available in the dry season, precisely at the time when fat content of land-based prey animals is at its lowest, which (in a confirmation of recent changes in dietary advice) make it a poor dietary choice, especially for nursing mothers.
Lastly, communities of women who dive in shallow water for a living in Korea and Japan remain fit for much longer than land based workers. There is no deterioration of their ability to work until around age 75. Women frequently continue to productively dive for a living into their 90s. People who do this or spend a lot of time in cold water get a bony growth in their ear canal called "Surfer's Ear". Identical growths are found in Homo erectus (ca 2 million years before present) and in both anatomically modern humans and Neanderthals, indicating a semi-aquatic lifestyle for all three.
The route modern humans took out of Africa ca 100,000 ybp followed the coastline and rivers, suggesting that water continued to be an important source of food, as it does right up the present day for many communities.
So the Aquatic Ape Hypothesis is now mainstream or rapidly becoming mainstream.
But predictably, despite spelling out the evidence and giving an example of a testable hypothesis that has been tested and shown to be accurate, some scientists are still saying that the aquatic ape hypothesis is flatly wrong. It seems that no matter how much evidence accumulates, there is no evidence whatever. This kind conservatism and resistance to paradigm changes in science has been noted by historians of science. Max Planck once quipped that progress in his field occurred one funeral at a time, i.e. only as the old guard died out and were replaced by youngsters with nimbler minds.
Extra notes
Observations in want of an explanation that the Aquatic Ape Hypothesis explains.
Lack of body hair when other great apes are hairy, and many aquatic or semi-aquatic mammals, like hippos, are not.
Subcutaneous fat layer (blubber) when no other ape or land mammal has it, but marine mammals do.
Presence of exostosis (aka "surfer's ear") in fossils. It occurs with frequent immersion in cold water.
Bipedalism. When on land any early attempts at bipedalism carry significant evolutionary disadvantage (on two legs our ancestors were slower, less manoeuvrable, and more visible to predators). Watch a chimp on it's back legs and you see what the problem is - they are fucking awkward! The advantages of carrying stuff in our hands was minimal at first. Also other apes are routinely bipedal when wading in water.
Vernix (waxy substance covering newborns). Also found in seals, but in no other land mammal.
Stone tool cut marks on fish bones ca 2 million year bp, and other fossil evidence showing a substantial part of our ancestors diet was from the water
Diving reflex in infants newborn to 6 months
Breath control. No other land based mammal can hold its breath!
Boesch, C., et al. (2016), Chimpanzees routinely fish for algae with tools during the dry season in Bakoun, Guinea. American Journal of Primatology. doi:10.1002/ajp.22613
See also the crab eating Macaque via BBC's Planet Earth documentary series.
Crab eating macaques also use simple tools.
And there is another amphibious monkey, the proboscis monkey (Nasalis larvatus) of Borneo (via New Scientist).
FYI, an update of the "littoral dispersal model" (Munro 2010), a more correct term than "aquatic ape". Paleo-environmental & comparative fossil data suggest 3 overlapping theories:
Mio-Pliocene hominoids incl. australopithecines did NOT live in dry savannas, but in wetlands, wading & climbing vertically in above-swamp branches – aqu-arboreal theory,
Pleistocene Homo did NOT endurance-run, but followed African & Eurasian coasts & rivers, beach-combing, diving & wading for littoral, shallow aquatic & waterside foods incl. shellfish – littoral theory,
late-Pleistocene H. sapiens reduced diving, and mostly waded & walked bipedally, fishing & collecting with long straight legs & complex tools – wading theory.
Pliocene Epoch 5.333 million to 2.58 million years BP.
Pleistocene Epoch 2,588,000 to 11,700 years ago
Some relevant recent papers:
J.Joordens, S.Munro cs 2014 Homo erectus at Trinil on Java used shells for tool production and engraving, Nature doi 10.1038/nature13962
M.Verhaegen, S.Munro 2011 Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods, HOMO J.compar.hum.Biol.62:237-247
S.Munro 2010 Molluscs as ecological indicators in palaeoanthropological contexts, PhD thesis Univ.Canberra
J.Joordens cs 2009 Relevance of aquatic environments for hominins: a case study from Trinil (Java, Indonesia), J.hum.Evol.57:656-671
M.Gutierrez cs 2001 Exploitation d’un grand cétacé au Paléolithique ancien: le site de Dungo V à Baia Farta (Benguela, Angola), Compt.Rend.Acad.Sci.332:357-362
K.Choi, D.Driwantoro 2007 Shell tool use by early members of Homo erectus in Sangiran, central Java, Indonesia: cut mark evidence, J.archaeol.Sci.34:48-58
S.Cunnane 2005 Survival of the fattest: the key to human brain evolution, World Scient.Publ.Comp.
M.Vaneechoutte cs eds 2011 Was Man more aquatic in the past? eBook Bentham Sci.Publ.
P.Rhys Evans cs eds 2013-2014 Human Evolution conference London May 2013 proceedings, special editions Hum.Evol.28 & 29
M.Verhaegen 2013 The aquatic ape evolves: common misconceptions and unproven assumptions about the so-called Aquatic Ape Hypothesis, Hum.Evol.28:237-266,
2 July 2019.
Bonobo diet of aquatic greens may hold clues to human evolution. BioMed Central.
report on this article
Gottfried Hohmann, Sylvia Ortmann, Thomas Remer, Barbara Fruth. Fishing for iodine: what aquatic foraging by bonobos tells us about human evolution. BMC Zoology, 2019; 4 (1) DOI: 10.1186/s40850-019-0043-z
