Category Archives: science

medical, science

Oddity of the Week: Chimerism

One person outside but two people inside. That’s the gist of the chimera, a human being who carries the DNA (and sometimes the body parts) for two. It sounds crazy, but it happens. In fact, doctors think it probably happens more often than we realize. Unless there were some reason to test the DNA from cells in different parts of your body, you could easily be a chimera and never know it.
A chimera is a single organism composed of genetically distinct cells. This can result in male and female organs, two different blood types, or subtle variations in form. Animal chimeras are produced by the merger of multiple fertilized eggs.


Tetragametic chimerism occurs through the fertilization of two separate ova by two sperm, followed by aggregation of the two at the blastocyst or zygote stages. This results in the development of an organism with intermingled cell lines. Put another way, the chimera is formed from the merging of two non-identical twins. As such, they can be male, female, or have mixed intersex characteristics.
This can produce an organism with totally different characteristics on each side of the body: different genders or different colouring — as in the budgie above. Or it can cause mozaicism where the organism contains patches of the different cell types, something most easily spotted in coat colouring — as in the human above — or eye colour.
But very often the mosaicism is there; we just don’t know it.

natural history, photography, science

Oddity of the Week: Bats

Bats roost in big groups in caves. Wrong! If you’re a Hardwicke’s woolly bat, you prefer to sleep in a more luxurious — and private — place.
Kerivoula hardwickii roosts inside tropical pitcher plants. These carnivorous plants usually attract insects, but Nepenthes hemsleyana lacks the scents that others have, so few bugs are lured in. Instead, it benefits from the faeces of this tiny bat, which provides more than a third of its nitrogen and may be crucial to the plant’s survival.
These bats found a niche that no-one else was occupying; they are the only bat species known to roost in pitcher plants.


To take [the image above, and others] Merlin Tuttle waded through tropical forest peat swamps on Borneo. Once he had found an occupied plant, he would spend a few hours taming a bat before snapping it from his portable studio, which provided protection from heavy rains. “It only takes a small fraction of a second for a bat to either enter or emerge, so capturing the action at just the right moment is a real challenge,” says Tuttle.
Within a few days, the bats had learned to bump against his nose when they wanted him to give them some mealworms. “We were quite amazed at the intelligence of such tiny animals,” Tuttle says. “Contrary to common misconceptions, bats in general are gentle, highly intelligent and trainable.”
It is the fact that wild bats are so easily trainable that really struck me!
From New Scientist, 21 February 2015 and at www.newscientist.com/article/mg22530090.100-tiny-bat-makes-home-in-a-carnivorous-plant.htm.

natural history, science

Oddity of the Week: Frilled Shark

‘Living fossil’ caught in Australia
A group of fishermen got a bit of a shock when they pulled a rare Frilled shark out of the water.
The Frilled Shark, Chlamydoselachus anguineus, which looks like a cross between an eel and a shark, was caught near Lakes Entrance in Victoria in water 700m deep.
It was estimated to be around 2m in length. The common name of Frilled Shark comes from its six frill-like gill slits, the first pair of which meet across the throat, giving the appearance of a collar. It’s seldom seen, and may capture prey by bending its body and lunging forward like a snake.
The origins of the species are thought to date back 80 million years.


Simon Boag, of the South East Trawl Fishing Association (SETFA), told ABC News: “It has 300 teeth over 25 rows, so once you’re in that mouth, you’re not coming out. I don’t think you would want to show it to little children before they went to bed”.
He added that it was the first time in living memory that the species has been seen alive by humans.

From Practical Fishkeeping, www.practicalfishkeeping.co.uk.

science

Oddity of the Week: Bloody Beet

Sugar beets are the latest in a long line of plants found to produce haemoglobin.
Haemoglobin is best known as red blood cells’ superstar protein — carrying oxygen and other gases on the erythrocytes as they zip throughout the bodies of nearly all vertebrates. Less well known is its presence in vegetables, including the sugar beet … In fact, many land plants — from barley to tomatoes — contain the protein … Scientists first discovered them in the bright-red nodules of soybean roots in 1939 but have yet to determine the proteins’ role in plants in most cases … Plant haemoglobins might … serve as a blood substitute for humans someday … Or they could be exploited to trick our senses … as an ingredient in veggie burgers to make them taste more like bloody steaks.
From Scientific American; February 2015

natural history, science, words

Word: Gynandromorph

Gynandromorph
An organism that contains both male and female characteristics.
The term is mainly used in the field of entomology where butterflies occasionally occur displaying both male and female characteristics because of sexual dimorphism.
A gynandromorph can have bilateral asymmetry, one side female and one side male, or they can be mosaic, a case in which the two sexes aren’t defined as clearly (as in the calico lobster below).
As well as insects, cases of gynandromorphism have also been reported in crustaceans, especially lobsters, in birds and very occasionally in mammals.


Gynandromorph is derived from the Greek gyne female + andro male + morph form.
Note that gynandromorphism is different from hermaphroditism where only male and female reproductive organs are present as in, for example, some slugs and snails.

science

Oddity of the Week: Underarm Odour

Scientists have discovered that a gene called ABCC11 determines whether people produced wet or dry earwax. What is even more curious is that people who produce the “dry” version of earwax also lack a chemical in their armpits that bacteria feed on to cause underarm odour. And it seems that this gene is the single determinant of whether you do produce underarm odour or not.
Strangely while only 2 percent of Europeans lack the gene for smelly armpits, most East Asians and almost all Koreans lack the gene.
From: Tia Ghose, “People without Gene for Underarm Odor Still Wear Deodorant” at www.scientificamerican.com/article/people-without-underarm-protection/.

beliefs, ramblings, science

On Eating Animals

2 Comments

A week or two ago Virginia Hughes wrote a series of blog posts on personhood for National Geographic. One of them was about our relationship with our pets. In it she says:

When it comes to animals, my choices are full of contradictions and hypocrisies. I eat meat, wear leather, and endorse the use of animal models in medical research. On the other hand, I’m totally taken with the growing body of research demonstrating that non-human animals have cognitive skills once thought to be uniquely human. I believe animal cruelty is wrong and, as regular readers know all too well, I consider my dog part of the family.

Yes, in general I agree with this, although I’m not so happy about the use of animals in medical research. I can see that it is necessary to do some initial drug testing using animals and that behavioural studies could be useful, but these have to be well controlled and strictly necessary. Which is why research institutions have Ethics Committees. That doesn’t necessarily mean I like it. But we must not be using animals for testing things like cosmetics, household cleaners etc.
I fully admit that it is hypocritical of me to eat meat and wear leather when I expect others to rear, slaughter and butcher the animals for me. This is not a comfortable position.
I know that were I to have to procure my own meat then I would never eat beef, pork, lamb etc. again. I could despatch a fish. I could probably smack a bunny on the head, or top a chicken, but couldn’t deal with anything bigger. And I would have to be driven to even this by real, real hunger.
There are few, if any, things I can kill with a clear conscience. Even things I detest, like maggots, I still dislike killing. We gaily believe that these “lower animals” are not sentient. But are they? We have no way of knowing. And if some are, where is the line to be drawn between those that are and those that aren’t. As Virginia Hughes says, the more we learn about animals the more we realise is going on in their heads.
It is a perennial moral and philosophical dilemma.
While I wouldn’t go as far as some Hindu sects who won’t eat meat or eggs because they may be the reincarnation of an ancestor, I do feel that all living creatures deserve respect and have as much right to life as humans. If this is so, who can blame a tiger for killing and eating a man, when we will kill and eat a sheep, cow or pig?
Where I do draw the line is the gratuitous killing of animals, for example hunting or angling as a fun pastime. Hunting animals for food, done as humanely as possible, is one thing. Killing for the sake of it is, in my book, well out of order.
If we are going to eat meat then the least we can do is to try our best to ensure the animals have our respect in life (eg. good farming etc.) and a humane end. There is much to be said for the traditions in some ancient cultures of honouring the meat one is eating. Something which has been perpetuated in Christian circles as the saying of grace before meals. To this end we usually, at least at main meals, drink a toast to whatever noble beast we are eating.
Honour your enemies, for they too are humans beings. And similarly honour the animals you eat for they have given their lives to give you life.
Basically, respect all life. Indeed respect the whole of Nature.

amusements, links, science

Your Interesting Links

More links to interesting articles you may have missed.
Have you ever wondered how glow sticks work? Well wonder no more because here’s the explanation. I love those aromatic dye molecules; they’re similar to the ones I used when I was a post-grad student.
So chemicals are bad then? Well not so much. Five myths about the chemicals.
Want to avoid getting cancer? The Cancer Code provides a 12 point guide to avoiding unnecessary risk.
OK so let’s have something a bit more light-hearted …


Feral pigeons can be a pain, especially in cities, but wood pigeons (above) make wonderful contribution to our countryside. “That eat excellent”, too!
Rats! Nasty, dirty, disease-ridden creatures aren’t they? Well actually they aren’t dirty at all though rats do carry all sorts of unknown bugs. But then so probably do many creatures. We just don’t know, because we haven’t looked.
What looks like a rabbit, stands on two legs and walks? No, not Bugs Bunny but an extinct giant kangaroo. Yes, this one was basically too big to hop efficiently and was adapted to walk.
And while we’re on strange things in the animal world, here are five surprising facts about squirrels, including that they make jerky!
Most Brits will probably remember the wildlife film from some 15 or more years ago of squirrels beating an obstacle course to get food — if only because a well known brand of beer used it for a commercial! Seems Americans don’t know it, because one journalist conducted a human vs. squirrel battle of wits. And yes, the squirrels won!
Liz Heinecke specialises in hands-on science for kids which can be done at home.

Why is it we all love pizza? What makes it so irresistibly delicious? Turns out it is all down to the chemistry of the ingredients and the cooking.
Anthropologists have been arguing for decades about how the Pacific Islands were colonised. Now it seems that the voyage of the Kon-Tiki was misleading and that the Pacific islands were colonised from the west by skilled navigators, as the genetics suggest.
Back to something more serious for a minute. George Monbiot takes his weekly side-swipe at big business and big politicians.
Meanwhile we’re all getting lonelier as families and communities are becoming more fragmented. And the loneliness isn’t good for us. George Monbiot (again) concludes that our lives are becoming nasty, brutish and long.
Finally I’ll leave you with a couple of less serious items.
First a look at fictional characters who would have been vastly improved by an abortion. At last someone agrees with my jaundiced view of the classics.
And finally Paris’s giant inflatable butt plug Christmas tree was deflated by saboteurs and is now an oversized green condom.
p1s p2s

books, medical, science

Book Review: The Incredible Unlikeliness of Being

1 Comment

Alice Roberts
The Incredible Unlikeliness of Being: Evolution and the Making of Us
Heron Books, 2014
Alice Roberts is Professor of Public Engagement with Science at the University of Birmingham, and is perhaps the outstanding scientific polymath of our age: medic, anatomist, anthropologist, archaeologist, television science presenter and no mean artist. The Incredible Unlikeliness of Being is her latest book and sets out to unfold for us the amazing way in which we develop as an embryo and foetus and some of the ways in which we have probably evolved to this. And what an amazing voyage we are taken on!
I found the book immensely interesting and very readable. Roberts’ style is light, airy and chattily personal, while being scientifically accurate and informative — at times amusing and even ribald: how many authors could get away with a section entitled “Mind the Bollocks”? In fact I found the book so readable I had to ration myself to one or two chapters a night otherwise I would have devoured it in a single all night read.
We are taken on a journey from conception to birth with a look at how all the major systems of the body develop throughout pregnancy from the single egg and the successful sperm to the birth of a baby. Along the way Roberts describes the embryology, including insights from her own two pregnancies and the medical tests she has had done on her in the interests of science.
But more than this, she also discusses the archaeological evidence for how and why evolution has given us the kit of parts we have; how evolution got to produce them; and why they are different from other species. Right at the beginning of the book Roberts discusses the various theories of embryos and how babies are built from Aristotle to the present day. She is at pains to point out that each of these theories was consistent with the state of knowledge at the time so we shouldn’t scoff at them for being ignorant — one day our theories will be considered equally backward in the light of new knowledge.
Yes, I thoroughly enjoyed this book, but that doesn’t mean I don’t have reservations about it. It is a book for the scientifically (specifically, medically) literate layman. Roberts, rightly in my view, calls things by their correct scientific and medical names but I felt too often missed the opportunity to explain those names; what the part is or does. Of course the downside of providing more explanation is that it could disrupt the flow of the text (and make for a larger, more expensive book).
However I think there is a solution, at least in part, to this problem. The book is illustrated by Roberts’ own delightful line drawings — a very real demonstration of her skill as an anatomist! But there are for my money far too few illustrations. There were many occasions where I felt that a drawing (or other illustration) could have made the text much more powerful: especially in cases where the anatomy of different species, or at different stages of development, is being compared. Yes, some of those drawings are there, but for me too few. And drawings could have been used to explain some of the otherwise unexplained. In this respect I wanted more.
My other gripe is one which I all too frequently have to level at modern publishing (rather than authors): the poor quality of the paper used. Yes everyone wants to keep cost down and at £19.99 for almost 400 pages in hardback this is at the cheaper end of the spectrum. But oh that poor quality paper, which will not stand the test of time.
These are, however, relatively minor complaints about a book which I found informative, hugely interesting and immensely readable. I definitely came out somewhere different to where I went in!
So if you are interested in how babies grow in the womb, and how we got to be the shape we are, then I would thoroughly recommend this book.
It really is just so unlikely that we are all here, and as “normal” as we are!
Overall Rating: ★★★★★