Paleo diet: the myth

A good friend recommended me to look up the paleo diet after reading yesterday's post. So, while I was eating my breakfast, I searched it on YouTube, and foud this excellent TEDx talk about why the paleo diet is nonsense.




The paleo diet is basically an idea that we humans should go back to eating more like the pre-agricultural humans. It claims that eating primarily red meat, while avoiding high-sugar agricultural foods and dairy products, is the healthiest and most natural diet for humans.

However, this falls short on multiple points.

First, consider how short average life spans the ancient humans had. Sure, the world was much more dangerous for humans back then, and many probably were killed by predators, the weather, or other factors, but I doubt everyone would have been. The average represents the whole, so unless some died extremely young and the rest lived extremely long, in which case the average hits a vacuum in the middle, we should consider the posibility that their typical lifestyle limited their natural longevity, while some may have died prematurely as a result of predation or other adverse conditions.

The rest is explained in the video, which I warmly recommend you to watch. It basically covers how we humans actually are not adapted to eating mostly meat. Rather, we are deisgned to feed primarily on plants. However, toady, we have many processed, high-sugar and low-fibre plants that are not good for us, and this is probably what sparked the myth that a plant-based diet is bad for us. Surely, if you eat unhealthy plants, you will not be very healthy – that is just common sense! But eating whole foods, including the less juicy bits, is much better for us, as the fibres are essential for the health of our intestines, which in turn is critical for us to take up nutrients effectively.

Don't get me wrong though: there are parts of basically all plants that we should not eat. But eating some of the chewier bits that are edible improves your health. Also, as the video points out, many wild varieties of the vegetables and fruits we know today are not very useful to humans; most of our plants have been modified by selective breeding to produce more of the parts we like and less of what we do not need.

That is all I really wanted to say. Please enjoy the show!

Healthy foods in prehistory?

My day has been a lot about health and nutrition. Though I wouldn’t say I’m a health freak, I do enjoy healthy eating and exercising. We all know that eating healthily equals to eating vegetables and fruits more than anything else, while a broad and varied diet is essential. Human society provides a fantastic array of food varieties, at least in the developed countries.

But what would it have been like in prehistoric times? I do not only mean just before humans, but way back in the history of our planet.

I don’t really have anything figured out, only that question resonating in my head, and I am keen to find some answers, but do not have the time tonight. So, here I will present only a few ideas that have popped in my head at the moment.

A key fact to note is that the angiosperms (flowering plants), which produce all vegetables, fruits and seeds we find most of our nutrition in, were only present in significant abundance for the last 100 million years. The flowering plants provide such nutritious foods because they use it to attract animals to help spread their seeds or pollen; that is the sole reason they present such rich, juicy rewards. Before that, there were few, if any, organisms that would do such a thing – they would not display parts of them to be eaten!

So, this poses the question of where the nutrients would have been found before the angiosperms evolved. It may very well be that other plants had plenty of nutrients in them, but not as concentrated in specific parts, but rather more spread out. As a result, the herbivores would have needed to eat more of the plant in order to obtain sufficient levels of nutrients. I have no support for this idea, however.

Remembering an interesting side note from a lecture in soils – that most of the nutrients in modern rainforests are locked in the high canopies, while the soils are poor – made me think about the Carboniferous period, where the forests, restricted to humid, swampy coastal areas, were dominated by humongous ferns, club mosses and horsetails that had evolved tree-like forms. In our rainforests, the trees grow extremely quickly, shooting their leaves high up in a race to get to the sunlight. Because they grow so fast, they quickly absorb and assimilate most of the nutrients that are released to the soil by decay of dead organic matter, leaving the soils virtually depleted of nutrients. The same spatial arrangement of nutrients probably also occurred in the Carboniferous forests.

It is curious then how animals could thrive in these primitive forests. It is typically said that plants had to colonise land before animals, because they provide the base of the food chain. However, (if I am not completely mistaken), there were no large or even medium-sized herbivores until much later, in the Permian period. It seems the animals did not feed primarily on these plants. In that case, what did they eat? Other animals? Quite likely, but what did the animals that were eaten by those other animals eat in the first place? (Surely, there must have been low-growing vegetation around, but enough to feed entire ecosystems? Maybe, maybe not.) Did they perhaps eat fungi and other degraders? Would they have been nutritious enough?

Finally, I should mention, as a side note, that these questions relate mostly to land-based ecosystems. In the oceans and lakes, the story is different, since nutrients may be freely available floating around with the currents; many animals filter these directly from the water. Moreover, planktonic primary producers (i.e. organisms that produce organic food by photosynthesis, floating around in the water column) have probably been around since the dawn of life, first as cyanobacteria, and later as various other forms. So, in aquatic ecosystems, most nutrients will either be at the bottom, where decomposers release them from dead organisms that have sunk down, or suspended in the water.

Reflection

Yesterday, I forgot to publish the post I had written. Ironically, I was writing about how well it has worked to persevere with publishing every day! So, today will be a double day, the second post to follow shortly.

I was amazed to notice that I have managed to keep the daily blogging up for now over two weeks! So, today will be a day to relax and reflect upon these weeks.

Part of me feels pride over the d thus far, but another part is glad to know that it wasn't as demanding as I had first feared. Sure, a couple of times I have had to write some posts on my phone or on a school computer (I'm not used to an English keyboard... keep pressing the wrong buttons, having trouble finding symbols, and so on), which is less... comfy, but doing so taught me that (a) it is really not that tricky once you get into it and (b) ideas and inspiration can come when you lest expect it and it is important to be able to capture those thoughts the moment you have them.

Most importantly, though, I feel that this is re-sparking my natural curiosity and passion for paleontology, which has been smothered by academic studies, and still is to some extent. I feel it is rewarding, because I find it exciting - a sensation I thought was lost forever.

Speaking of reflection, have you ever wondered why your reflection in the mirror is inverted from left to right, but not up and down?

A short one on how T. rex used its arms

As with my earlier post on the scavenger/hunter debate, this entry aims to inspire you to think rather than to provide you with exhaustively researched facts. Therefore, please bear in mind that the facts mentioned here might be outdated; it might be sensible to double-check with a more reliable, well-referenced source for pure information.

Tyrannosaurus rex is famous for its characteristically short forelimbs with only two fingers, and their use has puzzled paleontologists for a century. It is known that they had fairly powerful muscles, so they clearly must have served some purpose – otherwise, those muscles would have been a waste of tissue, a pointless investment of muscle growth, which most likely should have been done away with through natural selection.

So, the scientists ask themselves: what were they used for? Several sugestions have been made, including holding a mate in position during copulation; (somehow) holding struggling prey while killing it with massive jaws; assisting in getting up from sleeping position (proposedly sitting on its belly).

However, I feel that these proposals fall short in explaining the next logical question: why did the arms become short? and why did they lose one finger? If they were used for grabbing things or for pushing the body up from the ground, why would they atrophy?

An explanation for the selection pressures that may have caused the reduction of T. rex's arms focuses on balance: the arms became shorter as a trade-off for growing a larger head, in order to avoid getting front-heavy.

Now, there is another way of maintaining balance while letting the front of the body grow heavier: growing a longer and/or thicker tail. But, a point to note is that the more weight you place far away from the centre of the body, the more effort and time it will take to turn the body, especially while running! So, if you were to do this, you would compromise agility instead of arm range. It seems T. rex preferred to let its arms dwindle than become awkwardly clumsy. Could this 'choice' tell us something about the underlying purpose of the shortened arms?

The enlargened skull is most likely an adaptation for hunting and/or feeding, and the choice to reduce the forelimbs rather than extending the tail suggests that (some measure of) agility was desired, probably in order to take or hunt down prey. The fact that the arms were atrophied in favour of hunting-focused adaptations might hint that the arms were not used much for hunting, perhaps not for grabbing at all. What else, then?

Another result of shortening the arms and losing a finger, rather than enlarging the tail, is saved tissue investment. This is an acceptable justification for shortening them if they are longer than necessary to do whatever it is they were used for, regardless of having balance difficulties or not.

Considering the above, the idea of the arms being used to help T. rex getting up from a sitting position seems the more plausible, in my view. The arms may have been just long enough to assist lifting the bulk of the body just high enough to allow the powerful legs to take over comfortably and raise the animal to full standing position, and two fingers might have been sufficient to give a decent push-grip on the surface.

Having in mind what I wrote about the need for every animal to reach ground level with their heads in order to drink, which is essential for survival, as we all know but tend to forget, I also propose that T. rex's arms may have been used to help getting up and/or down to the lake or river bank for a drink, not just for sleep. Powerful arms to boost the efficiency of getting up could potentially reduce T. rex's vulnerability to ambush while drinking.

Although I personally find that the experts may be focusing their efforts on hypotheses that are too narrow or even missing the point, maybe not even asking the right questions will give us a clear answer to the mystery of T. rex's stubby arms.

Silly scientific titles – or – Interdisciplinary vade mecum of contemporary scientific terminology and comprehensive nomenclature conventions: an example from comparative in situ geomorphometric transnecrotism

I just love making up ridiculous scientific-sounding nonsense titles! And it’s really easy if you have just been exposed to enough real, serious titles and scientific terms, and add a bit of creative sarcasm.

And what is even more fun is when I make up a title that is actually not entirely nonsense, but it sounds hilarious anyway. For example, my good friend Nigel asked me for advice on a topic to give a speech about, and, knowing that he is not fond of mammal paleontology, I suggested “mammalian cranial morphological innovations in the late Eocene and implications for stratigraphic bias”.

So, I thought today I could just spark some ideas of how to design your own excruciatingly protracted titulary grammatical units.

Long words always help. Take the longest, most complicated synonym for a word you can find. If they are esoteric, even better! An easy way of making words longer and more esoteric-sounding is by adding typical scientific pre- and suffixes, such as:

• inter-
• intra-
• trans-
• micro-
• macro-
• psycho-
• neuro-
• synchro-
• proto-
  

• -ology
• -morphology
• -morphism
• -osis
• -metric

… and many others I cannot think of at the moment

Naturally, you should try to use these thoughtfully, so you don’t end up making words such as neuroconcertmorphology, because, although hilarious in isolation, they may fail to convey the sarcastic seriousness an ideal scientific nonsense title should have. Perhaps neurocortical concert-affiliated osteomorphology, or transneurotic concertational morphometrology are better candidates, but again, I can understand if these would be too ridiculous too.

I think another hint is to use many big words, but say nothing. Neurocortical concert-affiliated osteomorphology could be an example of this. It can of course be developed by adding more restriction words, to narrow the nonsense down to an even more incomprehensive level: Transatlantic neurocortical concert-affiliated osteomorphology of basal cervids from the Younger Dryas. This title is about the concert-related bone structure associated with the part of the brain that processes sensory information, in primitive deers from one of the glacial periods, making a comparison across the Atlantic ocean. You might want to skip the concert bit to make the title more serious; it is up to you, really.

I don’t think there is much else to tell for now. My final suggestion is to practice, and immerse yourself in weird titles every day, and soon you’ll be an expert in silly scientific titles.

Crazy plant genetics

Although I’m not usually that keen on genetics, I can’t but be mesmerised by the awesome genetic ability of plants.

Since my genetics class before university was mostly focused on animals, I tended to forget that, being so different to animals at the anatomical and physiological level, plants are something else entirely in terms of genetics too.

I repeat: genetics is not my thing. Therefore, I will not have the confidence to go into any detail here, but if this grabs your attention – which I hope it does – it would be fun if you tried out my tips for researching, in a recent post.

First of all, plants are experts at asexual reproduction, i.e. cloning themselves, sort of like most bacteria and other unicellular organisms do, but more complicated. A perhaps familiar example of how they do this is vegetative propagation, basically spreading out underground roots wherefrom new plant individuals bud out. This ability helps them to quickly colonise a new area.

Now, I know for myself that I would instinctively think that cloning does not have much to do with genetics, since it is just making a copy of everything. The genetics we learned about in class was all about sexual reproduction, which is mixing genetic material from both parents into an offspring and how that works.

Cloning sounds simple in comparison. However, at university, we have learned quite a bit about gene activation – different genes being turned on at different times. This is crucial for animals, since our bodies change as we age: some genes are turned on early, others later, and some are turned off after a certain time. But, try to imagine the gene activation mechanism required for creating a clone of a complex, multicellular organism. In animals, the offspring starts from zero, (mostly) unattached to the parents, whereas the plant clones literally grow out of their parent, which is already developed enough. I may just be wrong, but I think that the clones quickly catch up with their parent in development, which means their gene activation sequence must be different. (They are clones in the sense that they have the same total set of genes – the same genome – but the way these genes are activated is what determines what the individual will look like, so if they are used differently, the clones can become radically different, or, in this case, similar even though they should be at different developmental stages. In basic genetic jargon, we would say the clones have the same genotype, but may have different phenotypes, whereas in this case, they would be expected to have different phenotypes, but they purposefully don’t.)

Plants are of course also able to reproduce sexually, which is how they adapt to their environment in a selective way, rather than by random mutation. A mutation is a spontaneous change in the genome of an organism. Some are quite familiar to us, such as the trisomy 21, or three copies of chromosome 21, in humans, which causes Down’s syndrome. I mention this mutation in particular because it shows that mutations are not limited to some gene bases being copied wrong, resulting in a different protein, but also includes accidents in cell division, where the genes may not have separated as they should. In trisomy 21, of the four copies of chromosome 21 that are meant to split evenly into the four sperm cells, a par did not separate, so one sperm ended up with two, and another one without a chromosome 21. If the sperm with the extra chromosome 21 enters the egg, which has its own copy of chromosome 21, the foetus will most likely develop trisomy 21.

This example results in an unfortunate condition for the child, but some of these mutations can work wonders. Most big leaps in evolution are thought to have been caused by large (and lucky) mutations of this kind.

While such crazy genetics can cause harm, or, as in most cases, prevent the zygote (fertilised egg) from developing at all, or maybe not have any effect at all, on the rare occasion, it produces something entirely novel. The Cambrian explosion, an event in the very early stages of animal evolution, saw a myriad of radically different animals emerge, so different from one another that the experts have no clue of how to classify many of them. It might have been full of such mutation events. (Hadn’t thought of that until writing this post actually, but it has given me something to think about now!)

In plants, at least two radical mutations of this sort have marked the rise of a whole new type of plants, which today dominate the flora. These mutations were even more crazy than getting and extra chromosome, though: they experienced a whole-genome duplication, i.e. a doubling of all chromosomes, all genes. I doubt any animal species would survive this, at least not with fertile offspring that could spread it to following generations – but plants did this twice, and moulded it into their perhaps greatest evolutionary inventions! I think they deserve an applause for this!!

The first whole-genome duplication event in plants occurred in the Late Carboniferous (Pennsylvanian), about 320 million years ago, and resulted in the emergence of seed plants, i.e. plants which encase their sexually produced offspring in a protective capsule, the seed, with enough moisture and nutrients to be able to lie dormant (‘inactive’) in the soil for long periods of time, enabling them to survive dry seasons and wait for optimal conditions before germinating into a seedling. The seed was perhaps the key innovation that freed the seed plants from their reproductive dependence on stable water bodies, and enabled plants to colonise land completely. Prior to this event, plants were only able to live by coasts and around nearby lakes, and, thus, animals were equally limited. The advent of seed plants enabled life to break free from the sea and move further inland, bringing complex life to all corners of the Earth. It turned out to be one of the most significant cornerstones in the history of life on this planet. How awesome isn’t that?!

The second time this happened, in the Early Jurassic period, roughly 190 million years ago, the world saw the first flowering plants, or angiosperms. (However, I remember reading a very recent article where scientist have found angiosperm-like pollen dating as far back as 240 million years ago, which is the Middle Triassic, so maybe this whole-genome duplication marked the emergence of more awesome angiosperms, or perhaps the dating methods are inaccurate.) The flowering plants are hugely important for us animals, since their strategy of recruiting animals to spread their seeds and pollen, helping them reproduce, means that they must be generous in providing nutritious rewards in the form of fruits and vegetables. (We also eat some of their seeds and roots, which the plants are not as happy about…) In other words, the flowering plants provide much better food for herbivores, which brings more easily available energy and nutrition to the food chain.

I have not yet read the paper about these whole-genome duplications, which I found ages ago, so I cannot give you much details. However, I am excited to learn more now, and I might just add another entry about this later. I hope it inspired you too. Respect plants!

Biology field course next year

In our second year, we paleontology students at the University of Bristol get to do quite a lot of field work. We did a one-week trip focused on geological mapping just before term start. Around the end of April, we will have a fossil-oriented field trip for another week, which I am quite looking forward too!

We will also have a field trip with the biology class this year, since we are a so-called Joint Honours programme, meaning that we take classes from two departments, in our case the departments of Earth Sciences and Biological Sciences. We were given a choice among a wide range of field trips, laboratory workshops and even a public outreach project, and I have just found out which one I have been allocated to.

In early April next year, I will be going to Lagos, a town in the Algarve coast of southern Portugal. We will spend a week studying all sorts of plants, and how they are adapted to their environment! The first few days will be led by our supervisors, to familiarise us with the plants and the setting, to appreciate how we can study them, and to give us ideas for the independent group research project we will spend the remaining time on.

I'm quite thrilled to see what a biology field trip will be like, as I have never had a serious biology-focused excursion before. I am also excited to see the Mediterranean sea!

A gut feeling tells me I should get some new field gear – adapted for work under blazing sun, rather than pouring rain and freezing wind. Self-moisturising notebook, rather than a (hardly) water-resistant one. Lots of water. Moist snacks...

I'll have plenty of time to think about it!