Tag Archives: evolution

Calling all science-y parents

It’s been a while since I posted on The Skeptical Dad. Since around the time our second one – a sceptical daughter – came along, in fact.

It turns out that having children vastly diminishes the time and energy for properly researched blogging. Or for anything, for that matter.

Who’d have thought?

I’ve got a stack of ideas jotted in random places and half-written posts waiting to be worked on. So I’ll get back to regular postings from now on.

Promise.

For now, here are a few things I’ve noticed in the last year or so, which might be interesting to science-y parents.

 

ExpeRimental

From The Royal Institution, the UK organisation dedicated to scientific education:

ExpeRimental is a series of short films that make it fun, easy and cheap to do science at home with children aged 4 to 10. Our films give you lots of ideas for kids’ activities that will help you explore the world around you, question and experiment together. We’ll show you how to do the activity and how to make sure adults and children get the most out of it. Tell us how you get on and share your photos and any funny things your kids say!

What I like especially about ExpeRimental is that it’s not just a series of fun activities (though it is) but it teaches a real scientific approach. By tweaking variables, predicting what will happen, then observing the effects, it takes these practicals from demonstrations to experiments.

Citizen science

The brainchild of Sophia Collins and funded by The Wellcome Trust, Nappy Science Gang is taking a citizen science approach to answer some key questions.

…it will be the first citizen science project where the users set the research priorities, design their own protocols (with advice from scientists) and then run their own experiments. We’ll find out some useful science for cloth nappy users (a growing group as the environmental imperatives become clearer), and we’ll tackle a lot of persistent urban myths, with scientific thinking and evidence.

Find out more and get involved at the Nappy Science blog and Facebook page.

Introducing kids to evolution

Here’s a great resource for books on evolution and Charles Darwin aimed at kids, courtesy of Evolution for Kids!

 

Happy science-ing!

What can Mickey Mouse tell us about a growing child?

At a party some time ago, I got talking to a biology graduate friend about comparative psychology, as a geek tends to do at social occasions.

Comparative psychology is the study of animal behaviour and mental processing across different species. By doing this, it gives us clues to the function, benefit and development of a particular behaviour. Understanding the similarities and differences amongst different animals in this way can shed light on evolutionary relationships.

The topic came up because our friends were revelling in how cute baby animals are. If you don’t believe me, just look at these cherry-picked examples:

Author: George Estreich

Baby monkey

Author: Ville Miettinen

Baby fur seal

Author: Matt Stanford

Baby elephant

Author: uaeveggies

Baby duck

What’s striking is how wildly different baby animals can provoke the same “aaah” reflex. Baby primates and baby birds, separated from each other and from us by millions of years of evolution, can elicit the same cooing reaction. And size doesn’t seem to matter − a 100kg baby elephant can bring as much infatuation as a 5kg baby seal.

In other words, there’s something about being a baby, and not just a miniature version of an adult.

This immediately reminded me of an image drawn by Nobel prize-winning animal behaviourist, Konrad Lorenz. It shows how juvenile proportions are conserved across different animal groups, and goes someway to explain why we react to many baby animals as we do.

From Studies in Animal and Human Behavior, vol. II, by Konrad Lorenz, 1971. Methuen & Co. Ltd.

From Studies in Animal and Human Behavior, vol. II, by Konrad Lorenz, 1971. Methuen & Co. Ltd.

I think I first saw this image in a book by renowned evolutionary biology, Steven Jay Gould*. He also included it in a wonderful essay called Homage to Mickey Mouse. In this article, Gould explains that over time, to chime with his softening of character, Mickey’s appearance became increasingly juvenile.

via Zoonomian

A large head relative to body, short legs and feet, bulbous cranium and big eyes, as seen in a latter-day Mickey, look like the hallmarks of a juvenile. And Mickey travelled this path to juvenility in reverse − a phenomenon known as ‘neoteny‘.

An illustration’s fine, but to truly demonstrate this scientifically, Gould actually measured the relative changes in Mickey’s physical attributes and plotted the results on a graph. The result, as was Gould’s wont, is an engaging fusion of science and creative writing − do read it. (On reading, I did wonder whether Mickey’s appearance was altered to match a desired change in character, or the other way round.)

The key to all this is that the proportions of a baby’s face, as compared to an adult, are similar across many different animals. This set of features triggers what Lorenz described as an ‘innate releasing mechanism’ − an automatic and consistent reaction to an important behavioural cue. It makes sense that a hard-wired mechanism has evolved to trigger an immediate sense of attachment when confronted with a baby’s face − it will promote parental care, which has clear evolutionary advantages.

But that same hard-wired mechanism also appears to fire when we see similar baby-ish proportions in other animals. It’s an inappropriate response in an evolutionary sense, but it’s better to be harmlessly fooled by a baby bird than to not feel instinctively drawn to our own baby.

What’s fascinating is that, in some cases at least, these ‘releasers’ are reduced to very specific features. A classic example was demonstrated by Lorenz’s Nobel prize-winning collaborator, Niko Tinbergen, using three-spined sticklebacks. A male stickleback will attack another male, as identified by a red belly, but will also attack any object with a red spot − fish-shaped or otherwise. A stickleback-shaped object without a red belly is suitably ignored. Like a red rag to a stickleback, it’s better to be safe than sorry.

Babies do something similar in reaction to stylised smiley faces − a circle for a head, two dots for eyes, and a curved line for a mouth is enough to grab a baby’s attention. This stays with us into adulthood and is, for better or worse, the reason why emoticons are so enduring. So, similar to a stickleback reacting solely to a red spot, it seems it’s not a whole baby’s face we respond to, just a certain set of features.

Yes, your baby’s cute because of this graph:

“At an early stage in his evolution, Mickey had a smaller head, cranial vault, and eyes. He evolved toward the characteristics of his young nephew Morty (connected to Mickey by a dotted line).” By Steven Jay Gould

* I should dedicate this post to the late, great Derek Yalden, who taught me zoology at The University of Manchester and told me to read The Panda’s Thumb.

(As an addendum: none of this makes animals we find cute any more ‘worthwhile’ than “ugly” animals. Check out the recent campaign by the “Ugly Animal Preservation Society“.)

Do all babies start off female?

There was a bit of coverage last week in the scientific and popular press about some research that appears to refute the idea that the human Y chromosome could disappear at some point in our evolutionary future. In early mammals, the Y chromosome was the same size as the X chromosome but, during the course of our evolution has shrunk to a fraction of the size. This has led to the theory that the Y chromosome could disappear altogether if this shrinking carries on, but the new study has challenged this notion by showing that Y has, in fact, remained a fairly stable size over the last 25 million years. It seems that we may be arriving, or have arrived, at the bare essentials – the non-critical genes have been stripped away over time and natural selection has preserved the vital ones.

The jury’s still out on whether the Y chromosome will become extinct – “we won’t nail it without a crystal ball”, said Professor Darren Griffin of University of Kent in a Guardian article – but this sparked a memory of a conversation I had a while ago about what it is to be ‘male’ or ‘female’.

Some of wife’s friends had been debating whether or not all babies “start off as females”. This debate arose, I guessed while desperately trying to recall my high school biology classes, because of the fact that all fertilised embryos develop along the same path, regardless of the genetic make-up of the embryo. This is until certain genes on the Y chromosome (if present) are activated at around eight weeks and male-associated hormones, chiefly testosterone, are produced that act on some cells to start forming male-specific organs. Without these hormones kicking in, which is the case  in XX embryos when no Y chromosome in present, the cells in the developing embryo go on to form female-specific organs. This means that fertilised embryos under normal circumstances will develop female-specific sex organs unless a hormone cue is activated that signals otherwise.

So all embryos are female, then?

Hmm, perhaps not. One can still make a genetic distinction between males and females at the very point of fertilisation – XX chromosomes will give rise to females and XY will lead to males – and this remains static throughout an individual’s development (and, indeed, life). There are, however, some clinical oddities that throws some confusion into the mix. Some males, for instance, have two X chromosomes but develop as males instead of females because of the presence of a third, Y chromosome that contains the genes to provide the male hormone cues (“Klinefelter’s syndrome“).

So could we define maleness as the presence of at least one Y chromosome (some males are XYY too)?

Not really, because that definition comes unstuck when we consider individuals who are XX but develop as males (at least outwardly), due to the gene for the male hormone cue being copied to one of the X chromosomes (“XX male syndrome“), or individuals who are XY but develop as females, due to a defective Y chromosome (“Turner syndrome“) or mutated Y genes (“Swyer syndrome“).

This leads to complications when trying to enforce a purely genetic definition of gender. The International Olympics Committee for years attempted to enforce this view to adjudicate on cases of gender uncertainty, believing that this represented a more definitive and less intrusive test than physical examination. In this Y-centric definition, without ever meeting an individual and having only a few of their cells, the presence of the Y chromosome or any of its genes (such as the male sex determining gene called ‘Sex-determining Region Y’ (SRY)) would lead to the conclusion that those cells came from a man.

However, for the reasons I mentioned above about all the genetic uncertainties, pressure from a number of medical associations in the USA thankfully led to this sort of test being dropped by 2000. A ‘one-or-the-other’ test of this sort simply does not fully account for the complexities of gender and can lead to discrimination and unfair impediment. The lead opponent of such gender screening, Georg Facius, even proposed a ‘third gender’ for those that could be considered both male and female. One instance where this could be applicable is in cases of “Androgen insensitivity syndrome“, in which XY individuals show abnormal responses to the masculinising hormone androgen. Because the effects can vary, some individuals are anatomically male but have reduced fertility (mild), some possess ambiguous genitalia (partial), while some are almost indistinguishable from XX females (complete).

Even going back to the possible demise of the Y chromosome casts doubt on this Y-centric world. The experts that do anticipate the disappearance of Y are not predicting the end of ‘males’, rather they envisage another sex determining mechanism will take over. This happened before the emergence of the Y chromosome (sex was determined by environmental factors, such as temperature, and still is in some reptiles) and occurs in mammals where the Y chromosome has disappeared (in spiny rats, for example, the male-specific genes have hitched onto other chromosomes).

And this is all before we get into the complex world of gender identity, such as when an individual of one gender is uncomfortable being associated with that gender, which may be environment-driven (or may not be, or may be a little bit). Nor have I touched on psychological and behavioural differences, which lie on a continuous and overlapping spectrum between males and females and are often socially defined (and therefore subject to variation and change).

So none of this means that an embryo is female before the male signals kick in. It is perhaps more accurate to say that an embryo is gender-neutral, i.e. neither male nor female, until towards the end of the embryonic period, at which point anatomical differences start to become apparent in the foetus. But even then, as highlighted above, someone may share characteristics of both sexes and remain ‘double gender’.

Which is all a long-winded of way of saying that a binary male-female distinction is a little fuzzy.