Tag Archive: biology

Aug 11 2018

Book review: Chrysalis: Maria Sibylla Merian and the Secrets of Metamorphosis by Kim Todd

merianChrysalis: Maria Sibylla Merian and the Secrets of Metamorphosis by Kim Todd has a self-explanatory title, it is about the life of Maria Sibylla Merian a scientific illustrator who lived 1647-1717, and the life cycle of insects – their metamorphosis.

“Scientific illustrator” does not feel like the right term for Merian. She actively collected insects, at all stages in their lifecycles to study how they developed. This involved learning how how to nurture the insects. Her illustrations showed the insects through the stages of their lives alongside the plants on which they lived and fed. This is close to a study of ecology which didn’t really gain recognition as an area of study until the early 19th century. In her fifties she spent a couple of years in Surinam where she continued her study of more exotic creatures.

She was born in Frankfurt where she lived until she married and moved to Nuremburg, also in what is now Germany. Her father, Matthäus Merian was an illustrator, as was her stepfather Jacob Marrel, her husband Johann Andreas Graff, was one of Marrel’s apprentices. In 1685 Merian left her husband to go to a religious community in the Netherlands (the Labadists in Wieuwerd) with her mother and two daughters. She left Wieuwerd in 1691 to live in Amsterdam where she stayed until her death in 1717, aside a two year trip to Surinam.

Surinam had been “visited” by Europeans in the 16th century, and the Dutch had gained control of it from the English in the late 17th century. The English got New Amsterdam, now New York, as a quid pro quo. The colony was under the control of the Dutch West India Company and Labadists had been amongst those that gone out to the colony, their stories returning with them to the community at Wieuwerd. Surinam was not unknown land but it was tropical, and the colonial government were keen to get people out to the country to make a more well-rounded society. Merian went there to study insects in the same way as she had done in Europe but was, to some degree foiled by the conditions: deep jungle, rife with disease. Nevertheless her study there led to the publication of her book: Metamorphosis insectorum Surinamensium. I must admit I’m rather tempted by this facsimile.

Merian received a good deal of encouragement from father and stepfather in pursing art but the guild and business systems of the time made it difficult for her to work professionally as an artist. She seems to have got by by forming relationships with a range of nature enthusiasts for whom she carried out commissions, selling her illustrations individually, and trading in specimens for cabinets of curiosities.

She appears to have been remarkably independent for the period. Caroline Herschel lived somewhat later than her in England but her work in astronomy was tied to her brother, William. Similarly her exact contemporary, Elisabeth Hevelius, who had her own reputation as an astronomer was closely coupled to that of her husband.

Merian lived in a time when the study of nature was evolving. People were still seriously asking whether certain forms of life appeared spontaneously (the Royal Society’s cheese mite experiments). Linneas had not yet created his nomenclature for living things. Gentlemen were populating “cabinets of curiosities” but they were disorganised assemblages of artefacts. She was a contemporary of Jan Swammerdam, Antonie van Leeuwenhoek and Robert Hook.

The past can be difficult to understand, the meanings of words can shift quite dramatically. For example, René Antoine Ferchault de Réaumur said “The crocodile is certainly a fierce insect, but I am not in the least disturbed about calling it one!”.

This is all to say that Merian could quite reasonably be described as working at the cutting edge of biology.

Merian is surprisingly well-documented, this seems to be as a result of a couple of factors. Her family were moderately high-profile and as publishers / illustrators naturally left substantial records. She published several books which were reprinted over the next hundred years or so, her illustrations appeared, sometimes unattributed, in other publications. A chunk of her papers were acquired by Peter the Great and ended up in St Petersburgh where they were re-discovered in the 1970s.

Her work seems to have attracted criticism in the early 19th century, on grounds of inaccuracy understandable, since by this time her books were over 100 years old. This criticism was possibly also driven by the changing character of naturalists, they were starting to professionalise, and no doubt also linked to her gender. Many of her male contemporaries had some funny ideas but this is often glossed over.

I enjoyed Chrysalis it covers Merian’s life in some detail whilst bringing in a good flavour of the times in which she lived and the people she interacted with.

May 06 2017

Book review: Where the Animals Go by James Cheshire and Oliver Uberti

animalsgoIt is becoming a tradition for me to receive a beautiful James Cheshire and Oliver Uberti coffee table book for my birthday. A couple of years ago it was The Information Capital, this year it was Where the Animals Go.

Where the Animals Go is a collection of stories and visualisations all relating to the tracking of animals, each story occupies at most a few pages and is accompanied by a couple of maps which trace the paths of one or more of the species in question across the earth. The maps are beautiful.

The book starts with an introduction which covers the evolution of animal tracking technology. The bulk tracking of the movement of animals on an hourly or faster basis has become easier with the advent of commodity GPS devices since the 1990s. Some of these raw data are now being published on aggregation websites such as Movebank.

Precursors to these GPS tracking systems are old-fashioned bird-ringing – a passive technique which relies on recapture of animals and has been around since the early 19th century. The Argos system relies on data from tags being transmitted to a small constellation of satellites – it has lower temporary and spatial resolution than GPS. There are also radio and acoustic tracking methods which have been around from the sixties.

In the text we discover how ants have been tracked in an artificial nest using tiny bar codes, and Daphnia zooplankton have been tracked with fluorescent nanoparticles in a tiny aquarium. Penguin colonies have been identified, and numbers estimated, from satellite imagery of the guano (posh word for poo) that they stand amidst.

I must admit to being a bit of an enthusiast for tracking myself, particularly when out skiing or walking. I used use GPS to geotag my photographs – parenthood has put a stop to such pursuits. I started using GPS about 10 years ago when the process was a bit clunky both in terms of the hardware and the software to process tracks. Nowadays I can record a GPS track on my watch or a mobile phone. So I can easily see how advances in technology relate to advances in the study of animal movement with GPS sensors becoming feasible for ever smaller animals.

After introducing the technology there are then three parts covering animals on the land, in the water and in the air.

The tracks of troops of baboons seemed most similar to the tracks of my Alpine skiing holidays. In this study a number of baboons from the same troop were tracked, this made it possible to see something of the leadership, or otherwise, behaviour of the baboons but this is actually unusual – in most cases a small number of individuals from a group are tracked.

Most entertaining are the tracks of animals who have been relocated for human convenience, and promptly return to the place from whence they came – pythons and crocodiles are in this group. Sadly, I suspect this type of behaviour does not end well for the animals concerned.

Related to this are those animals who live in close proximity to humans and find their why blocked by major highways, mountain lions in California – for example. Animal tracking can show the degree to which major highways cause a problem, and also show the way to solutions in providing corridors.

Sometimes tracking clears animals of what humans consider to be mis-deeds – the tracking, by acoustic sensors, of sharks in Hawaii falls into this category. More benignly it has been discovered that oilbirds in Venezuela did not simply foray out of their nesting caves at night and return at dawn, thus failing to carry out vital ecosystem services such as dispersing seeds. Instead GPS tracking showed that they spent days out in the forest foraging, and roosting in trees.

Generally the animals portrayed are depicted moving in a plane (mathematically speaking) across the land but sometimes they break out into the third dimension – an example is vultures spiralling upwards on thermals. Hang-gliding friends I know would be interested in this. Also included are the bar-headed geese, who migrate across the Himalayas, it turns out they generally stick to the lowest altitudes they can get away with, however they still exhibit great endurance in high altitude flying.

The accompanying text provides detail on what we see in the maps, and also some human interest in the scientists who collected the data.

Another beautiful book, and the references are sufficient for you to go and find out more about any of the individual stories. There is a dedicated website where you can see excerpts of Where the Animals Go.  

Feb 09 2017

Book review: I contain multitudes by Ed Yong

multitudesThis book was a Christmas gift, for which I’m very grateful! I Contain Multitudes: The Microbes within us and a Grander View of Life by Ed Yong is all about bacteria.

Bacteria are somewhat neglected in the popular science literature, I think the closest I can come is The Eighth Day of Creation by Maurice Freeland Judson which is about the discovery of DNA and its role in molecular biology in which bacteria and viruses play a part.

Yong’s book is about the relationship between bacteria and other organisms, humans included. It reveals a world where bacteria are not simply passengers on oblivious hosts but are a heavily integrated part of the host’s life cycle.

The study of the “microbiome” is relatively recent. Unravelling the members of a microbial community prior to the invention of cheap, and easy, DNA sequencing was hard. Carl Woese pioneered this approach in the 1970s, and used it discover the archea, a whole knew Kingdom of life (plants and animals are two of the other Kingdoms, to give you and idea of the magnitude of this discovery). Sequencing of the bacterial inhabitants of humans gained pace in the 2000s when it was discovered that we all carry a rich community of bacteria which varies from site to site around the body, let alone from individual to individual. What is true for humans is true for other organisms.

The book continues with an overview of how important bacteria can be to an organisms life. For example choanoflagellates, typically single-celled organisms, only form colonies in the presence of certain bacteria. And bobtail squid rely on bacterial partners to provide their luminescence. The standard lab animals (mice, zebrafish, flies) have been raised in germ-free environments and whilst they do not die, they do not flourish – even in the comfortable environment of the lab. The Wolbachia bacteria interferes with the sex lives of its insect hosts, it is only passed down via the eggs of the female and so it arranges by various means that there are more eggs and females than sperm.

These partnerships are not accidental, in the sense that organisms often provide specific structures to support their bacterial partners and exchange specific molecular markers with them. In some cases the host is essential to the survival of bacteria it contains because they have given up on carrying out tasks essential to their continued existence, for example in the supply of essential nutrients. This is true on many scales, animals from termites to cows have digestive systems designed to accommodate a particular bacterial support team to enable them to digest what would otherwise be food of low nutritional value. The early years of a human infants life are shaped by its acquisition of the right microbiome to prime the immune system and aid digestion.

The reason that bacteria are so effective in providing support services to their hosts is their high rate of evolution. Not only do they replicate fast, they have a promiscuous approach to DNA they come across in their environment. This means that if any bacterial species evolves a useful trait, such as the ability to digest seaweed then its neighbours in the gut can pick up that ability via its DNA. These genes can, eventually, end up in the genome of their hosts.

Japanese people who eat nori seaweed, which contains carbohydrates which the human body can’t digest on its own, host bacteria which can. Moreover, the genes those bacteria use to carry out this digestion were acquired from marine bacteria.

Yong is not misty-eyed about his bacterial subjects, as he points out their symbiosis with other organisms is not altogether harmonious – in the end the bacteria are in it for themselves.

The book finishes with some examples of how bacteria can be used to support human health, and speculates how this approach – currently only used in curing persistent C. difficile infections – could be extended to all manner of ailments including blood pressure and mental health problems.

I’ve been following Ed Yong on twitter for quite a while, and where he found the time to write a book as well as everything else he seems to do is a mystery to me! his style, as a science journalist, can be seen in the book, both in the presentation of the story, with brief character sketches of the scientists involved and quotes from them, and in the titles of the chapters which are entertaining but not necessarily informative. The book is thick with examples which build into larger themes, turn to the back of the book and you’ll find references to the primary literature.

Bacteria deserve our attention, this book is a great introduction to how they shape the lives of “higher” organisms.

Jun 29 2015

Book review: Gut by Giulia Enders

Gut-by-giulia-endersIt seems a while since I last reviewed a book here. Today I bring you Gut: The Inside Story of our Body’s Most Underrated Organ by Giulia Enders.

The book does exactly what it says on the tin: tell us about the gut. This is divided into three broad sections. Firstly the mechanics of it all, including going to the toilet and how to do it better. Secondly, the nervous system and the gut, and finally the bacterial flora that help the gut do its stuff.

The writing style seems to be directed at the early to mid-teenager which gets a bit grating in places. Sometimes things end up outright surreal, salmonella wear hats and I still don’t quite understand why. The text is illustrated with jaunty little illustrations.

From the mechanical point of view several things were novel to me: the presence of an involuntary internal sphincter shortly before the well-known external one. The internal sphincter allows “sampling” of what is heading for the outside world giving the owner the opportunity to decide what to do with their external sphincter.

The immune tissue in the tonsillar ring was also a new to me, its job is to sample anything heading towards the gut. This is most important in young children before their immune systems are fully trained. Related to the tonsils, the appendix also contain much immune tissue and has a role in repopulating the bacteria in the large intestine with more friendly sorts of bacteria following a bout of diarrhoea.

The second section, on the nervous system of the gut covers things such as vomiting, constipation and the links between the gut and depression.

The section on the bacterial flora of the gut gathers together some of the stories you may have already heard. For example, the work by Marshall on Helicobactor Pylori and its role in formation of stomach ulcers. What I hadn’t realised is that H. Pylori  is not thought to be all bad. Its benefits are in providing some defence against asthma and autoimmune diseases. Also in this section is toxoplasmosis, the cat-born parasite which can effect rats and humans, making them more prone to risk-taking behaviour.

I was delighted to discover the use to which sellotape is put in the detection of threadworms – potential sufferers are asked to collect threadworm eggs from around the anus using sellotape. I can imagine this is an unusual experience which I don’t intend to try without good reason.

There is a small amount of evangelism for breast-feeding and organic food which I found a little bit grating.

As usual with electronic books I hit the references section somewhat sooner than I expected, and here there is a clash with the casual style of the body of the book. Essentially, it is referenced as a scientific paper would be – to papers in the primary literature.

I don’t feel this book has left me with any great and abiding thoughts but on the other hand learning more about the crude mechanics of my body is at least a bit useful.

Apr 05 2014

Book review: Darwin’s Ghosts by Rebecca Stott

darwinsghosts_bookcoverCharles Darwin’s On the Origin of Species was rushed into print after a very long gestation when it became clear that Alfred Russell Wallace was close to publishing the same ideas on evolution. Lacking from the first edition was a historical overview of what went before, pertinent to the ideas of evolution. On the occasion of the publication of the first American edition, Darwin took the opportunity to address the lack. Darwin’s Ghosts: In search of the first evolutionists by Rebecca Stott is a modern look at those influences.

After an introductory, motivating chapter Darwin’s Ghosts works in approximately chronological order.  Each chapter introduces a person, or group of people, who did early work in areas of biology which ultimately related to evolution. The first characters introduced are Aristotle, and then Jahiz, a Persian scholar working around 860AD. Aristotle brought systematic observation to biology, a seemingly basic concept which was not then universal. He wrote The History of Animals in about 350BC. The theme of systematic observation and experimentation continues through the book. Jahiz extended Aristotle’s ideas to include interactions of species, or webs. His work is captured in The Book of Living Beings.

Next up was a curiosity over fossils, and the inklings that things had not always been as they were now. Leonardo Da Vinci (1452-1519) and, some time later, Bernard Palissy (1510-1590) are used to illustrate this idea. Everyone has heard of da Vinci. Palissy was a Hugenot who lived in the second half of the 16th century. He was a renowned potter, and commissioned by Catherine de Medici to build the Tuileries gardens in Paris but in addition he lectured on natural sciences.

I must admit to being a bit puzzled at the introduction of Abraham Trembley (1710-1784), he was the tutor of two sons of a prominent Dutch politician. He worked on hydra, a very simple aquatic organism and his wikipedia page credits him as being one of the first experimental zoologists. He discovered that whole hydra could regenerated from parts of a “parent”.

Conceptually the next developments were in hypothesising a great age for the earth coupled to ideas that species were not immutable, they change over time. Benoît de Maillet (1656-1739) wrote on this but only posthumously. Similarly Robert Chambers (1802-1871) was to write anonymously about evolution in Vestiges of the Natural History of Creation first published in 1844. Note that this publication date is only 15 years before the first publication of the Origin of Species.

The reasons for this reticence on the part of a number of writers is that these ideas of mutability and change collide with major religions, they are “blasphemous”. This becomes a serious issue over the years spanning 1800. Erasmus Darwin, Charles’s grandfather, was something of an evolutionist but wrote relatively cryptically about it for fear of his career as a doctor. I reviewed Desmond King-Hele’s biography of Erasmus Darwin some time ago. At the time when Erasmus wrote evolution was considered a radical idea, both in political and religious senses. This at a time when the British establishment was feeling vulnerable following the Revolution in France and the earlier American revolution.

I have some sympathy with the idea that religion suppressed evolutionary theory, however it really isn’t as simple as that. The part religion plays is as a support to wider cultural and political movements.

The core point of Darwin’s Ghosts is that a scientist working in the first half of the 19th century was standing on the shoulders of giants or at least on top of a pile of people the lowest strata of which date back a couple of millennia. Not only this, they are not on an isolated pinnacle, around them are others also standing. Culturally we are fond of stories of lone geniuses but practically they don’t exist.

In fact the theory of evolution is a nice demonstration of this interdependence – Darwin was forced to publish his theory because Wallace had essentially got the gist of it entirely independently – his story is the final chapter in the book. For Wallace the geographic ranges of species were a key insight into forming the theory. A feature very apparent in the area of southeast Asia where he was working as a freelance specimen collector.

Once again I am caught out by my Kindle – the book proper ends at 66% of the way through, although Darwin’s original essay is included as an appendix taking us to 70%. Darwin’s words are worth reading, if only for his put-down of Richard Owen for attempting to claim credit for evolutionary theory, despite being one of those who had argued against it previously.

I enjoyed this book, much of my reading is scientific mono-biography which misses the ensemble nature of science which this book demonstrates.

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