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Posts Tagged ‘Alfred Russel Wallace

Tanah Papua, the bird paradise

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There are few simple pleasures to compare with watching birds of paradise display and perform, even if it’s only on video – and it would be pretty hard to see them otherwise. The forests of Papua are a wonderland for birds, and 39 of the 42 known species of birds of paradise are found only there. My attention was drawn to these very striking birds – in their very various ways – when I read Peter Raby’s biography of Alfred Russel Wallace several years ago, and I’ve associated them with exotic forest regions, miserable weather, malaria and an almost toxic other-worldliness ever since. A sort of anti-paradise doused with bewildering colour and cacophony.

The lineage of these birds has been hard to reconstruct, and apparent similarities to other birds, such as bower birds, have led ornithologists astray in the past. And to be scientific about it all, I’d have to master such concepts as order, family and clade, but I won’t go there in this post, except to say that the whole classification system looks a mess from the outside.. The most recent mitochondrial DNA research has set their ‘moment’ of emergence at about 24 million years ago. They’re quite close, genetically, to corvids, always a plus.

king bird of paradise (cincinnurus regius)

To an amateur, the most striking features of these birds are the plumage and displays of the males. And the females surely agree, even when they try to appear unimpressed. One immediately thinks of sexual selection – and Darwin. Here’s what Darwin had to say about the process, in The Origin of Species:

Sexual selection… depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring.

…when the males and females of any animal have the same general habits… but differ in structure, colour or ornament, such differences have been mainly caused by sexual selection

On the origin of species, 1st edition, pp88,89

One has to wonder why it’s the males who grow their weird and wonderful plumage and create their elaborate dances to attract the females, and not the other way around. Generally the female coloration – and that of both sexes when young – has evolved so that they match and blend in with their surroundings. The males are taking serious risks in drawing attention to themselves in this way, which is why the differences appear late – as secondary sexual characteristics. In fact, males generally mature later than females, by quite a wide margin. But since they don’t bear the offspring the males are more dispensable. It’s interesting to note, in this light, that in polygamous species, birds are sexually dimorphic both in appearance and lifespan. That’s to say, monogamous birds tend to look alike and to have the same lifespans, whereas in polygamous species, the females live longer. In fact this is the case in all species, not just birds. The San Diego zoo, which specialises in this family, tells us that birds of paradise can live for some 30 years in captivity – but surely it would be tougher in the wild, especially for males.

Not all birds of paradise are polygamous though – they have a range of breeding systems, of which the most interesting is ‘lek-type polygamy’. Lek is a Swedish term which refers to fun activity bound by the loosest of rules. It was first used in a book about the avian life of that region back in the 1860s, and is now adopted worldwide, and applies to a bewildering variety of species, including birds, bees, butterflies and bats (and various species of reptiles, amphibians and fish). And not just because they all like to have fun; the term has been refined to refer to specific behaviours. Two general types of lekking are identified – classic and exploded. They refer essentially to the physical space occupied – the lek. In a classic lek (a more or less circular region), each of the males is within sight of at least some of the others, whereas in an exploded lek, this isn’t ‘necessary’, as long as they’re in earshot. In fact, with some booming birds, like the New Zealand kakapo, they can be kilometres apart. In these exploded leks, the variety of behaviours is greater, as if the woo-ers are less inhibited by their neighbours.

Of course the leks in thickly forested Papua would be very different from Sweden. Sometimes the males share and compete in a common ground such as a forest clearing, while in other species they display and dance in the trees, controlling their territory vocally. Displays involve spinning, charging, freezing, hopping and skipping, hanging upside down, making show of their most irridescent plumes, all the kind of stuff imitated by the Folies Bergère, but with males rather than females as the beauties.

Breeding behaviour, though, is very varied. Not all male species are brightly festooned, and male-female relations run from bim-bam-thanks-mam polygamy to the sharing of nest-building and child-rearing among monogamous species such as the manucodes (they don’t all bear the bird-of paradise name – apart from manucodes there are sicklebills, riflebirds, parodias, astrapias and others).

splendid astrapia (astrapia splendidissima)

These birds are, unsurprisingly, and more than other types, very much tree-dwellers, preferring the high canopies and living largely off their fruits, so they need to have their forests protected. They’ve been hunted for centuries, and Wallace had no hesitation in killing as many as he could himself in the 1850s. Of course, being in straitened circs in those years, his income was largely dependent on producing exotic specimens for the home trade, and birds of paradise were like gold. But local tribesmen also valued the bright plumage as a status symbol. In recent times the popularity of the birds for twitchers has helped in their protection.

They’re a fairly raucous lot, and the striking, machine-like notes of riflebirds and sicklebills are very much worth listening to online. One might assume that in dense forest, loud calls to indicate location are a must.

magnificent riflebirds (ptilorus magnificus)

In conclusion, I began writing this to find out more about a particular family of birds, but got sidetracked by a lot of fascinating stuff I’ve only touched upon here, such as sexual selection, sexual dimorphism and anisogamy. More about all that in later posts, I hope.

Written by stewart henderson

July 28, 2019 at 1:24 pm

the anthropic principle lives on and on

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Believable-Creationism24c

The anthropic principle, the idea that the universe – and let’s not muddle up our heads with multiverses – appears to be tweaked just right, in a variety of ways, for the existence and flourishing of humans, has long been popular with the religious, those invested in the idea of human specialness, a specialness which evokes guided evolution, both in the biological and the cosmological sense. And, of course, God is our guide.

Wikipedia, God bless it, does an excellent job with the principle, introducing it straight off as the obvious fact that anyone able to ascertain the various parameters of the universe must necessarily be living in a universe, or a particular part of it, that enables her to do the ascertaining. In other words the human specialness mob have it arse backwards.

So I’ll happily refer all those questing to understand the anthropic principle, in strong and weak forms, it proponents and critics, etc, to Wikipedia. I’ve been brought to reflect on it again by my reading of Stephen Jay Gould’s essay, ‘mind and supermind’, in his 1985 collection, The Flamingo’s Smile. 

Yes, the anthropic principle, which many tend to think is a clever new tool for deists, invented by the very materialists who dismiss the idea of supernatural agency as unscientific, is an old idea – much more than 30 years old, because Gould was critiquing not only Freeman Dyson’s reflections on it in the eighties, but those of Alfred Russel Wallace more than a century ago, in his 1903 book Man’s Place in the Universe. Gould had good reason for comparing Dyson and Wallace; their speculations, almost a century apart, were based on vastly different understandings of the universe. It reminds us that our understanding of the universe, or that of the best cosmologists, continues to develop, and, I strongly suspect, will never be settled.

Theories and debates about our universe, or multiverse, its shape and properties, are more common, and fascinating, than ever, and accompanied by enough mathematics to make my brain bleed. The other day one of my regular emails from Huff Po science declared that maybe the universe didn’t have a beginning after all. This apparently from some scientists trying to grab attention in a pretty noisy field. I’ve only scanned the piece, which I would hardly be qualified to pass judgment on. But not long ago I read The Unknown Universe, a collection of essays from New Scientist magazine, dedicated to all ideas cosmological. I didn’t understand all of it of course, but genuine questions were raised about whether the universe is finite or infinite, about whether we really understand the time dimension, about how the laws that govern the universe came into being, and many other fundamental concepts. It’s interesting then to look back to more than a century ago, before Einstein, quantum mechanics, and space probes, and to reflect on the scientific understanding of the universe at that time.

A version of the universe, based on Lord Kelvin's calculations, used by Wallace

A version of the universe, based on Lord Kelvin’s calculations, used by Wallace

In Wallace’s time (a rather vague term because the great scientist’s life spanned 90 years, which saw substantial developments in astronomy) the universe, though considered almost unimaginably massive, was calculated to be much smaller than today’s reckoning. According to a diagram in Man’s Place in the Universe, it ended a little outside the Milky Way galaxy, because we had no tools at the time to measure any further, though Lord Kelvin, the dominant figure in physics and astronomy in the late 19th century, made a number of dodgy calculations that were taken seriously at the time. In fact, Kelvin’s figures for the size of the universe, and for the age of the earth, though too small by orders of magnitude, were considered outrageously huge by most of his contemporaries; but they at least began to accustom the educated public to the idea of ginormity in space and time.

But size wasn’t of course the only thing that made the universe of that time so different from our own conceptions. The universe of Wallace’s imagination was stable, timeless, and, to Wallace’s mind, lifeless, apart of course from our planet. However, he doesn’t appear to have any good argument for this, only improbability. And an odd kind of hope, that we are unique. This hope is revealed in a passage of his book where he goes off the scientific rails just a bit, in a paean to our gloriously unique humanity. A plurality of intelligent life-forms in the universe

… would imply that to produce the living soul in the marvellous and glorious body of man – man with his faculties, his aspirations, his powers for good and evil – that this was an easy matter which could be brought about anywhere, in any world. It would imply man is an animal and nothing more, is of no importance in the universe, needed no great preparations for his advent, only, perhaps, a second-rate demon, and a third or fourth-rate earth.

Wallace, though by no means Christian, was given to ‘spiritualism’, souls and the supernatural, all in relation to humans exclusively. That’s to say, he was wedded to ‘human specialness’, somewhat surprisingly for his theory of evolution by wholly natural selection from random variation. This is the chain, it seems, that links him to modern clingers-to the anthropic principle, such as William Lane Craig and his epigones, who must needs believe in a value-laden universe, with their god as the source of value, and we humans, platonically created as the feeble facsimiles of the godhead, struggling to achieve enlightenment in the form of closeness to the Creator, with its appropriate heavenly rewards. And so we have such typical WL Craigisms as ‘God is the best explanation of moral agents who apprehend necessary moral truths’, ‘God is the best explanation of why there are self-aware beings’ and ‘God is the best explanation of the discoverability of the universe [by humans of course]’. These best explanation ‘arguments’ can be added to ad nauseum, of course, for they’re all of a part, and all connected to the Wallace quote above. We’re special, we must be special, we must be central to the creator’s plan, and our amazingness, our so-much-more-than-animalness, in spite of our many flaws, suggests a truly amazing creator, who made all this just for us.

That’s the hope, captured well by the great French biologist Jaques Monod when he wrote

All religions, nearly all philosophies, and even a part of science testify to the unwearying, heroic effort of mankind desperately denying its contingency.

I think modern philosophy has largely moved on from desperate denialism, but Monod’s remarks certainly hold true for religions, past present and future. Basically, the denial of our contingency is the central business of religion. It’s hardly surprising then that the relationship between religion and science is uneasy at best, and antagonistic at its heart. The multiverse could surely be described as religion’s worst nightmare. But that’s another story.

Wallace: a life to celebrate

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Wallace in Singapore

Wallace in Singapore

This year marks the 100th anniversary of Alfred Russel Wallace’s death. I read a biography of the man a few years ago, and discovered a fascinatingly driven, indefatigable scientific adventurer, who shared Darwin’s dedication to scientific rigour, if nothing else. Far less ‘high-born’ than Darwin, he spent much of his early life living by his wits, which, luckily, were plentiful. He also spent a lot more of his early scientific life engaged in exotic field work in South America and the islands of south east Asia, suffering various illnesses and accidents and relying on precarious local hospitality. It was in the Spice Islands (the Malaku Islands, in what is now Indonesia) that, feverish with Malaria, he was struck by the essential concept of natural selection. Fever upon fever, what a moment that must have been! (Killjoy researchers, though are casting a sceptical eye on this romantic story – truth and romance – what an eternal battle).

I was thinking that it’s a shame, considering all that he must have experienced and reflected upon in those far-from-home years, that we don’t have from Wallace a travelogue to match Darwin’s Voyage of the Beagle – which I also read a few years ago and which is one of my all-time favourite reads. However, I’ve recently been reminded that he did write such a travelogue, The Malay Archipelago, which was enormously successful in his lifetime. I plan to read it this year, in honour of Wallace, just as I read Darwin’s book to mark the bicentenary of his birth in 2009. Also because they’re less tough reading than The Origin of Species (I got through about a third of it, many years ago) and Wallace’s Contributions to the Theory of Natural Selection (1870) and Darwinism (1889), which one day I might get to.

Meanwhile, it’s just been announced that about 4000 of Wallace’s letters, constituting some 95% of his surviving correspondence, have been brought together in a magnificent online project. Check it out.

Written by stewart henderson

January 28, 2013 at 11:16 am