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Cells, Microbes & Viruses / Re: Are there any unicellular organisms that prey on multicellular organisms?

« on: 28/06/2017 17:46:32 »

I guess this depends on how you define "prey on"...

Many types of bacteria (unicellular) consume multicellular organisms. For instance the "flesh eating bacteria" like MRSA that causes necrotizing fasciitis (don't look it up if you're at all squeamish!!!)

But this is an example of colonies of bacteria living on or in the multicellular organism (host), where each bacterium exudes digesting enzymes into the host, and then absorbs whatever comes out and eats it. This is a far cry from chasing something down, ripping it apart and ingesting it (which is what I visualize predation).

Actually, a web search revealed this article: http://onlinelibrary.wiley.com/doi/10.1111/1462-2920.12949/abstract which reports groups of unicellular protists (amoebae) "pack hunting" nematodes (a few thousand cells)

Pack hunting by a common soil amoeba on nematodes
...Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes...The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link ‘nematophagous protists’ in soil food webs.

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Plant Sciences, Zoology & Evolution / Re: Why birds stand on one leg when they rest and sleep?

« on: 14/05/2017 17:59:31 »

Minimising heat loss. Legs without feathers lose heat. Tucking one up into feathers helps to keep the bird warm.

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Physiology & Medicine / Re: Why do right handers stir their tea in a clockwise direction?

« on: 13/05/2017 03:50:43 »

Interesting. I have a different perception. In stirring outwards I need to move the whole wrist, which makes it much more unpleasant for me as it feels a bit clumsy and I need more engery for this. If I stirr inwards, I can accomplish the stirring by basically just moving my thumb and forefinger, which is a rather small movement.

I have, btw, this weird habit, that I need a spoon in my tea, even though I drink it without milk or sugar. Maybe the ruminant movement is one reason for this ;-)

Your first point demonstrates the difference between the precise, fine stirring technique of a German, versus the grotesque wrist gyration of an Australian...

The second thing is indeed quite weird. Do you enjoy the spoon stabbing you in the eye?

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General Science / Re: Why do I get stuck trying to dodge another pedestrian?

« on: 11/05/2017 10:00:34 »

Possibly a "goalkeeper reflex" is at work here. As soon as we detect the eye movement that precedes a body swerve, our first instinct is to move in that direction, defending our territory. At short range this can, as intended, lead to a collision.  I used to coach a brilliant junior fly-half who could break through a defensive line by looking left and running right. The trick of avoidance is to signal your intention as early as possible.

To avoid embarrassment in a pedestrian collision, always apologise in German. If the other bloke is German he will realise that you aren't, but will be so impressed with your social skills that he won't complain. If he isn't German, he will assume that you are, and not attempt to complain in English.

German goalkeepers, on the other hand, are a problem.

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Physiology & Medicine / Re: Why do we only get 2 sets of teeth?

« on: 09/05/2017 07:55:31 »

This is evolution. The primary or deciduous dentition (milk teeth) are much smaller and less numerous than the adult teeth; as such they can fit into a smaller jaw more readily, can be grown and deployed at lower resource cost and more rapidly.

But they are also softer and less resilient than adult teeth. Also, as the jaw grows, more than doubling in size as a person develops, more teeth are needed to fill the space and also to cope with tougher and bulkier food items that are required to sustain a bigger person.

Nature has compromised with two sets of teeth. The secondary dentition that replaces the milk teeth is bulkier, harder and there are more teeth. Historically these teeth have proved adequate to enable a person to survive beyond child-bearing age, which is the selection point controlling our evolution. As such, there is no reproductive advantage to having any more teeth beyond our secondary dentition, so it has never happened.

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Plant Sciences, Zoology & Evolution / Re: Do animals have weird dreams?

« on: 08/05/2017 12:01:38 »

It's quite difficult to establish exactly what an (awake) animal is thinking, and to validate our assumptions (using existing technology), given that most animals do not speak human. We can sort of make some broad assumptions about what an awake animal might be thinking based on the environmental situation and body/facial language patterns, but who's to know if we are completely wrong? It would be even harder to communicate with a sleeping animal, since there is largely an absence of body language during sleep. And they will never tell you what they dreamed about afterwards, in order for you to validate your theory.

Some dogs appear to run during their sleep. Whether they are dreaming about running through the fields, or if it's simply a spontaneous outburst of memorised muscle movement: hard to say. While it's easy to jump to the conclusion (with a little anthropomorphism) that a cat that licks its lips during sleep might be dreaming about food , I've never seen a cat chatter during sleep, as they often do while hunting birds, or hiss and swipe as they often do in a fight. So, if cats do indeed dream about these topics, it doesn't seem as though those dreams consistently translate into observable muscle movements.

What constitutes a "weird dream" anyway? In my (human) experience, a 'weird' dream is usually one in which the events or behaviours of the characters deviated from what is expected or socially acceptable. My opinion is that animals don't tend to have as many rules and expectations as humans have constructed for themselves. So, while we might think that waking up very late, walking around naked in public, eating some random old faeces, licking one's own anus, and then mating with a sibling would be a pretty crazy dream...perhaps not so weird if that any/all of that occurred in an animal's dream.

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The Environment / Re: Is sea level rising, or land sinking?

« on: 27/04/2017 19:31:46 »

I was pointing out that the climate research unit at Norwich polly was not one of the most prestigious places to do your accademic carrer and thus presumably did not attract the best minds in the world.

Given that you went to one of the best universties I expect you are ne of the cleverest. Why then do you accept without challeng the results of those who did a degree through the notoriously not very rigorous at all geography department of Norwich polly? I am happy to accept that they can have got it right and be the best in the world without going to Oxbridge but the lack of scrutiny that their results gets from you is very odd.

Do you really think that all the world's climate researchers, and all their data come from a rather small University  in Norwich?

I'm actually quite good at scrutinising things.
That's why I am able to point out that you keep posting nonsense.

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Just Chat! / Re: All purpose world

« on: 23/04/2017 16:52:24 »

What is the point of your post?

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Physiology & Medicine / Re: How does fructose malabsorption develop, and is it reversible?

« on: 23/04/2017 12:01:37 »

There seem to be very many unknowns still. There are different hypotheses about what exactly causes a malabsorbtion in fructose. Either the GLUT5 transporters are not working propperly or there are just to few. Maybe the exchange of signals that trigger the expression of mRNA and subsequently the production of GLUT-proteins is disordered. Or maybe it is something else. Maybe a combination of causes. People seem to work on this question but do not have a conclusive answer yet.

Sounds like you need to do more research.

Rab11a are GTPases which are key regulators of intracellular membrane trafficking. The literature suggests there is a dysfunction in Rab11a dynamics following GLUT5 transporter saturation - this downregulation of Rab11a recycling in intestinal epithelia alters GLUT5 trafficking to the apical membrane, which reduces mRNA expression of GLUT5 as well as it's baseline activity.

Any questions?

~

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Physiology & Medicine / Re: How does fructose malabsorption develop, and is it reversible?

« on: 22/04/2017 15:34:09 »

It sounds to me like you have given yourself a "dysbiosis"; essentially, the profile of microbes that inhabit the intestine is a product of our daily diet. Different foodstuffs select for different microbial populations, so the bowel flora shifts and adapts to the diet. It's almost certain that part of what we call "traveller's diarrhoea" is a rearrangement of your microbiome in response to the challenge of a novel diet.

If a person radically and abruptly changes what they are eating, the microbial spectrum shifts; the bacterial equivalent of a domino effect then ensues, with different bug profiles triggering changes in other bug populations; the changes slowly ripple through the populations and reset the "shape" of your microbiome.

If you then revert your diet, the microbiome does not instantly switch back to how it was before. It takes months to re-adapt. This is evidenced by people who "yo-yo" diet; it may take 6 months for the microbiome to switch from a pro-obesity profile to a lean profile.

The next episode of the Naked Scientists will be looking at some of these questions. We'll publish the link to the podcast as soon as it is out.

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That CAN'T be true! / Re: Are black people better dancers?

« on: 22/04/2017 11:11:20 »

There are structural differences as well as pigmentary differences between different groups of people, and I understand that the domination of track athletics by Africans and African Americans is due to having an elongated calcaneum and enforced Darwinian selection. But the question is overlaid by the cultural implications of "better". At the highest level the ballet tradition is most deeply ingrained in northern Europe, very few  westerners  of any color can match the average Russian male soldier's solo performance, and Balinese, Indian, Chinese and Japanese traditional female dancers need to be both petite and trained from early walking age. 

At the amateur level, recent immigrants to the UK have imprinted their parents' cultural acceptance of public dancing, particularly in the case of West Indian and African families, on the younger generation, whilst "native" whites seem to retain a Victorian diffidence towards public displays of enjoyment. Our traditions are quite different: Morris dancing, like cricket, is just an excuse for drinking beer, and Scottish dancing is more a political statement than a pleasure. No prejudice here - I do them all, rather badly.

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New Theories / Re: Is heterogenics is the sole purpose of sex?

« on: 20/04/2017 21:15:08 »

Are you denying that women are capable of orgasm during sex?

Nope, just denying that you provided an answer to the question asked.

Theres no other reason for clitoral bulbs to exist aside from clitoral mechanics enabling penetrative clitoral motion, its a matter of persuasion and practice which includes all forms of stimulation

So says you. Without any evidence. Or argument.

There are endless demonstrations of clitoral mechanics in high definition online, I encourage you to research in the name of science..

Moderator please remove the 'is' you added to my thread title

You are, unsurprisingly, dodging the real point: you have no citations, evidence, or arguments to support your claim about the purpose of sex or its value.

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Plant Sciences, Zoology & Evolution / Re: How is frogspawn fertilised?

« on: 15/04/2017 12:54:04 »

This is a fairly complex question to answer because there are many, many species of frogs and for almost anything you try to say about them, there is always a species that will break the rules. But generally, frog eggs are fertilised externally (outside the body). This is different again to other groups of amphibians. The female frog lays a cluster of eggs into water or a damp substrate, and the male deposits his sperm on top of the eggs. Microcopically, the surface of each egg cell has a specific 'zone' at which a single sperm can enter, and other areas where it is impenetrable. When a healthy, 'fit' sperm contacts the egg, it fuses with the egg's membrane. Some rather complex molecular and chemical signals start to happen at this point, which I won't get into (mainly because I don't fully understand them myself). Eventually the nucleus, containing the all important DNA of the male frog, is able to move into the egg where it can combine with the female's DNA, already in the egg and begin the process of forming an embryo.

Overall, the process is not too dissimilar from what happens internally in other species, including mammals, or externally in fish. Arguably, land animals that use internal fertilisation are the weird ones...

Most of the current knowledge is based on a few 'model species' (the ones scientists often like to study in the lab). But the more we learn about frogs, the more differences we are bound to find...and the less we are able to make a single, generalising statement about "what frogs do" because there are probably thousands of versions of frog reproduction out there.

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Plant Sciences, Zoology & Evolution / Re: How do birds reproduce?

« on: 14/04/2017 10:47:11 »

Hi Sarah,

Birds actually undergo internal fertilisation, like mammals, even though they lay eggs externally. The egg is fertilised well before it has a shell, or a 'white' or even the majority of the 'yolk'. The male's (sometimes males') sperm cells travel from the female's cloaca (the single main opening for urine, faeces and reproduction) towards the top of her oviduct, where mature eggs are deposited from the ovary (ovulation). There in the upper oviduct, sperm can either fertilise an ovum immediately or be stored in special tubes for later. Sterm storage occurs so that the female doesn't need to mate multiple times to fertilise a whole clutch (since ova are not all released at the same time), and also because it allows some flexibility in the exact timing of the mating event (she doesn't have to find the right mate at exactly the right time to match for her ovulation).

Each fertilised eggs then continues to develop and travel down the oviduct and uterus, gaining its yolk, white (albumen) and finally shell over about 20 hours, before finally being laid as a shelled egg. Apart from fertilisation itself, the egg's development is not all that dissimilar to making an unfertilised egg, which is why the unfertilised chicken eggs you eat are almost exactly the same as the fertilised ones at the farm.

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Plant Sciences, Zoology & Evolution / Re: Is evolution even science, or just gross intellectual dishonesty?

« on: 12/12/2016 17:50:19 »

Random acts, even if they might result in any benefits, will always result in far more chaos. For example, even if you believed that if you threw a pile of bricks off a roof billions of times they would eventually fall into a perfectly constructed house with walls, closets and an attached garage, a vast majority of the time, though, they would unquestionably fall into meaningless configurations.

Genes, chromosomes etc. are not bricks.  They don't just take on any random configuration and can only combine in certain ways.  They also are more analogous to the blueprints of the house rather than the building materials.  Mutations are small alterations to those blueprints.   Of course, you might instead be referring instead to the original formation of life, abiogenesis instead here.  But even abiogenesis is not just a random throwing together of chemicals, as those chemical themselves have rules that govern how they can join up.  Besides, abiogenesis and evolution are two completely different things and are not related to each other, even though some people try to lump them together into a single argument. (now that's intellectual dishonesty) 

The same is true with genetics. Randomly rearranging genetic material generally result in grossly deformed and diseased organisms. For every fossil of a viable-looking organisms we should have found billions of fossils of diseased and deformed organisms. They're not there. The vast majority of fossils show well-formed, functional-looking creatures. The fossil record proves beyond any question that evolution never happened.

Mutations are not the random remixing of genetic material. they are small changes to one part of the blueprint.  Some mutations are benign (the Siamese breed of cat is a result of a mutation that altered its pigmentation.),  Some will be harmful, and some will turn out to be beneficial. (if not immediately then at some later point.  If the mutation is harmful or produces a malformed individual, that individual will either not survive or won't reproduce, and the mutation never gets into the gene pool. (If it hadn't been for the fact that people found the unique pigmentation of the Siamese cat desirable, they would have bred it out instead of for it and you wouldn't see that breed of cat today)   Mutations effect individuals, while evolution effects populations.   Only those mutations that do not hinder the individuals reproduction will be passed on to later generations and spread out into the population as a whole. 
The mutation rate also is fairly low in any given population. (if it goes too high, you risk not producing enough viable offspring to maintain the population.) As a result, the number of undesirable mutations resulting is malformed individuals is going to be vert low compared to the population at large (And the majority of these won't survive infancy).  The fossil record is sparse when compared to the number of creatures that have lived in the past.  The conditions which produces a fossil happens rarely and the vat majority of the time a deceased animal leaves no lasting record.  Pure common sense tells us that if if the fossil record is only represents a tiny fraction of past animal life and that malformed individuals would only be expected to be a small fraction of that, that you would not expect to find "billions" of fossils of malformed individuals. To suggest otherwise is again to be intellectually dishonest.

Then, to say that evolution was not random, as some have suggested, yet still call it evolution, is as ludicrous as calling a bird a giraffe -- if it flies it's not a giraffe.

Evolution is the combination of small random mutations to the individual coupled with natural selection on the population level. Those mutations that do not hinder the individual's reproduction, are passed on, those that do, are not.  That's evolution; the slow alteration of a population over many generations.

The bottom line is the fossil records shows that new species make their first appearance as functional creatures, not as a result of survival of the fittest. Where are the myriads of "unfit" that should have existed? Such a sudden appearance of new, viable life forms, which is confirmed over and over by the fossil record, rather than support evolution, thoroughly disprove it.

"Unfit" is a relative term.  A creature that is unfit under one circumstance, is the fittest under another.    Let's take the  giraffe for example.  You start with an animal that grazes on low shrubs.  In a population you are going to have a certain genetic variation in terms of neck length. This will vary over a certain range, with necks too long or too short selected against.  But now the climate begins to slowly change and the low shrubbery is going away in favor of trees. Those animals with longer necks find themselves having a slight advantage over those with shorter necks. The shorter necked individuals can't compete as well, produce fewer and fewer offspring and this trait is selected against. A new "norm" has been established for neck length.  This also means that mutations that produce even a longer neck will be selected for, when earlier, it would have been selected against (the too long neck being more of a hindrance for a low level browser.)   So a really long neck is "unfit" under certain conditions, but more fit under others.  "unfit" doesn't equate to non-viable, but just not a good fit for the circumstances.  "Survival of the fittest", just means that those individuals that have a genetic trait that gives them a competitive edge, is going to be more successful, and be more likely to produce offspring and pass that trait onto later generations. 

All your arguments themselves have been a type of intellectual dishonesty known as the "strawman fallacy".   You have erected a "strawman" version of evolution and knocked it down rather than actually arguing against the theory itself. This is why people keep telling you that you need to learn about evolution and what it actually says. Otherwise you are arguing against some imaginary version of it that is of your own making. (And ending up looking foolish in the process.)