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Tommy Leung


Of Pigs, Chimps, And Dinosaurs
[Brace yourself, this is a long read]
It seems like ever since mid-2013, not a month goes by without hearing about what I would call "PigChimpMan theory" of human evolution. This "theory" has been lurking around for a while in its own obscure corner of the internet, but it initially came to the attention of a wider online audience via PhysOrg back in July 2013. However, the idea was well and truly launched like a dysfunctional bottle rocket in November 2013 into the mainstream when it was publicised by that bastion of rigorous science journalism, the Daily Mail. Subsequently, it had spread like a pandemic swine flu across other media outlets.

(BTW, I'm not going to link to those pages directly and give them the hits, but if you wish to see them, they can easily be found via a quick Google search)

But we're not here to talk about that, as the ridiculousness of that theory has been thoroughly addressed by +PZ Myers
And it was also addressed on episode 420 of Skeptic's Guide to the Universe (

To say that the originator of the "PigChimpMan theory" has some odd and misguided notions about evolution would be an understatement and it is not on the basis of the "PigChimpMan theory" alone. No, lest you think we are talking about a one-trick wonder, fear not - he also has a website call Macroevolution Dot Net (once again, I'm not linking directly for reasons stated above). This is where he has published many other "theories", though admittedly most of them appear to simply be a variation on a very simple theme, namely "X did the nasty with Y and ended up with Z"

Okay, some #realtalk  here - cross species hybridisation does happen - for example, a mule is a hybrid between a donkey and a horse, and there are also hybrids between domestic cattle and American bisons, and even hybrids between false killer whales and dolphins.

He claims that such hybrids lend support for his "PigChimpMan (and other similar) theory". However such hybrids are often sterile and only occur between species which are closely related - often from the same genus. The "PigChimpMan theory of human origin" is based on a faulty, slippery slope assumption that since hybridisation between closely related species is possible, then species across entirely different orders can readily hybridise. Just because two closely related species can form hybrids does not mean animals from entirely different orders (or entirely different classes as you'll see below) can produce reproductively viable hybrids. Basically, just because there are mules running about doesn't mean that Manx cats came from a rabbit humping a cat.

Oh, I forgot to mention that didn't I? That the creator of Macroevolution Dot Net thinks that Manx cats are actually cat-rabbit hybrids? Just FYI. But cross-order hybridisation is nothing comparing with his proposed origin of the monotremes (platypus and echidnas) which involve birds hybridising with mammals. Yes. Your read that right. He thinks that the echidna exists because a hedgehog got it on with a kiwi. Don't take my word for it - go to his website and check it out for yourself.

But it doesn't end there (it never does), let me present his "They look kinda alike to me" theory of evolution. He has some very strange ideas about dinosaur evolution which I am sure scientists like +Michael Habib or +John Hutchinson or +Darren Naish or just about anyone else who have at least some interest in and background knowledge about dinosaurs would find, well, questionable to say the least. For example, did you know that according to Macroevolution Dot Net, pangolins evolved from stegosaurs?

His "theory" pretty much amount to "Pangolin looks kinda like a Stegosaurus. An anatomically inaccurate Stegosaurus from an old kids book about dinosaurs I came across. And if I ignore just about everything about both animals. Therefore, I think pangolins are actually descended from dinosaurs and Stegosaurus is a mammal" Go check it out for yourself - I seriously, seriously cannot make this stuff up even if I tried. He thinks that pangolin plates are homologous* with the plates of Stegosaurus and that the tail spikes on the thagomizer of the stegosaur tail actually belong on the feet and were homologous to the pangolin's claws.
*A homologous structure is a one which is found in different species that share a common ancestry; for example, our arms are different from the wings of a bat - both have been modification for different purposes in our respective lineages - but they share a common basic architecture from a common ancestor.

He also claims that:

"The modern giant armadillo is so similar to the ancient ankylosaurs that it is only reasonable to suppose it is descended from them."

According to his theory, thyreophoran dinosaurs are in fact mammals. Well, I guess by that logic, one can claim that it is only "reasonable" that dolphins are descendants of ichthyosaurs, right? Right? Well...when he is not busy trying to claim one group of reptiles are mammals, he is also trying to claim that one group of mammals are in fact reptiles. The mammals in question are the cetaceans - whales.
While he is not exactly claiming that dolphins are evolved, modern ichthyosaurs, he does think that whales had evolved from mosasaurs. The mosasaur were a group of extinct marine reptiles which are related to modern monitor lizards and snakes that lived during the late Cretaceous period ( and they are essentially a lineage of lizard-type reptiles that had adapted to the aquatic environment.

Despite extensive fossil AND molecular evidence for the actual evolutionary origin of whales, he still cite his "They look kinda alike to me" theory of whale evolution, while being unfamiliar with something call convergent evolution ( whereby divergent groups of organisms have independently evolve very similar forms as they lived in similar ecosystems/environment and were subjected to similar evolutionary selection pressures.

If you want to read up on the non-unhinged theory about evolution of whales, this Wikipedia article has a good collection of links and references you can look up and read at your leisure:

Oh, one more little thing - he also has this annoying habit of repeatedly following and unfollowing people on Twitter to try and get them to follow him back. +Steven Hamblin called him out on this, to which he claims that it was "an accident" (he has also deleted all his tweet correspondence with Steven), but others have mentioned that they have been subjected to the same "follow-unfollow" cycle from him.
I think I'm currently in the third or fourth "follow" cycle from him, though I suspect this post might terminate that altogether.

To lighten the mood a bit after this very long post/rant, I would like to propose a new genre of internet literature call "Macroevolution Dot Net Fan fiction" (I think I have just invented the worst kind of fan fiction). Here are some potential title to start off with, but feel free to make your own.

Loris = Monkey + Owl hybird
Ambulocetus = Otter + Crocodile hybrid
Sea cows = descendants of placodonts (

Then again, he is probably working on those very ideas right now...
Sharing for +ScienceSunday 
#sciencesunday   #pseudoscience   #evolution   #evolutionarybiology   #scienceeveryday   

Accompanying photo is "The Listener" (2013) by Patricia Piccinini. You can see the rest of her artwork here:
Photo was taken by Ars Electronica and used here under Creative Commons license (CC BY-NC-ND 2.0). Original here:
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Worth noting that the Skeptics Guide to the Universe chose the "man-chimp-pig" story as one of the worst science failures of 2013, alongside such luminaries as "vaccines make you gay" and "bigfoot DNA". Lots of angels singing in this choir:
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Call Of The Sirens
Earlier, I recorded an episode of Creepy but Curious - a regular radio segment on ABC New England that I go on every month to talk about weird and wonderful animals. This week, I talk about Sirens - which are eel-shaped, fully-aquatic salamanders that live in freshwater habitats in south eastern United States and northern Mexico. As usual, I also drew the art that goes with the radio segment which you can see below. To find out more about the Sirens, follow the link below to download an MP3 of that segment.
#scienceeveryday   #sciart  
While most amphibians are completely carnivorous as adults, the Siren enjoys a little 'salad on the side'
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Clams Containing Contagious Clonal Cancerous Cells
Some of you might remember might previous post about contagious cancers occurring in dogs ( and in Tasmanian Devil ( Now, another possible case of clonal contagious cancer cell line has been discovered, but whereas the previous known examples have been from mammals, this comes from a very different type of animal - clams.
To find out more, see this post by +Ed Yong 
In the 1970s, scientists noticed that soft-shell clams along the east coast of North America were dying from a strange type of cancer. Their blood, which was typically clear, would fill with so man...
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Parasite Perfume
Malaria is caused by single-cell protozoan in the genus Plasmodium and it is one of the most successful parasites in the world. It uses the mosquito as a site for sexual reproduction, as well as a flying hypodermic syringe to inoculate any hosts that the insect feeds on with infective stages of the parasite.
While female mosquitoes would usually feed on blood as a source of protein for egg development, she also feed on sugar as a source on energy, and her main source of the latter usually comes in the form of nectar. While Plasmodium already resides in one of her food source (blood), it seems that it can maximise its chances of encountering a mosquito by causing the host to also emit a lemony perfume which mimics the mosquito's other food source - nectar.
To find out more, see this post by +Carl Zimmer 
#scienceeveryday   #parasitology  
P.S. See also this post written by one of my students in 2013 about how a species of malaria may cause its bird host to become more attractive to mosquitoes.
Parasites are life's great success story, abundant in both species and sheer numbers. One secret to their success is the ability that many parasites have to manipulate their hosts. By pulling strin...
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Well, they're probably healthier than malaria, but you know, each to their own...
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Shrimp of Prey
I came up this speculative evolution creature while reading the recently published paper which described Aegirocassis benmoulae - a 2 m long filter-feeding anomalocaridid that lived during the Ordovician period. 
Together with species such as Tamisiocaris borealis which lived during the Cambrian, and the many other species of post-Cambrian anomalocaridids, they show that these extinct arthropods had occupied a much wider range of ecological niches than we had previously expected. 

So did the anomalocaridids evolved other ecomorphs that we we don't know about (yet)? Many large filter-feeders, such as the baleen whales, or the filter-feeding pachycormid fishes which lived during the Mesozoic, evolved from ancestors that were nektonic macrophagous predators (predators that cruise the mid-water for small to medium-size prey). Indeed the authors of the paper described A. benmoulae as one such example, having evolved within a clade of predatory anomalocaridid. 

So what other examples of convergent evolution which are comparable to those in modern oceanic fauna which might be found among the anomalocaridids? We already have a giant filter-feeder in the form of A. benmoulae, what about a pelagic, fast-swimming, macrophagous anomalocaridids? A large(-ish) streamlined predator that filled a similar ecological niches to that occupied by tuna, billfish, mako sharks, and oceanic dolphins today.

This is Lamnicaris - or how I imagine an anomalocaridid that occupied that niche might have looked like, swimming in the sea alongside A. bemoulae. It is named after the the Lamna - the Greek word for fish of prey, which in turn was named after Lamia of Greek mythology. The front grasping appendages of Lamnicaris are very robust, armed with serrated spines for cutting up prey. Those appendages are usually tucked away for streamlining and Lamnicaris only extend them when it is within close proximity to its prey.

The streamlined head-shield is inspired by that of Hurdia and the pair of "fins" situated just behind the head - which functions like dorsal fins on tuna or Mako sharks - are based on those found on Schinderhannes bartelsi. Taxonomically, Lamnicaris is in the Hurdiidae family alongside Aegirocassis benmoulae and Hurdia spp.
#SciArt   #scienceeveryday  
I came up with this bit of speculative evolution while reading the recently published paper which described Aegirocassis benmoulae - a 2 m long filter-feeding anomalocaridid that lived during the O...
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Under The Skin
I have written a new Parasite of the Day post! This one is about a rather large parasitic nematode that lives under the skin of the pygmy sperm whale - Kogia breviceps.
#scienceeveryday   #parasitology   #parasitismeveryday  
During this blog's first year back in 2010, we featured a parasitic nematode (roundworm) that lives in the placenta of sperm whales of all places. Today, we're featuring a study on another nematode which lives in the sperm wh...
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Egg Wars
Most people who look at a bird's nest might not think much of it, but it can be the front line of a perpetual battle that has been fought over many millennia between brood parasites and their hosts. Brood parasites are birds like cuckoo and cowbirds that have evolved to use other species of birds to raise their young.
This of course comes at a cost to the host bird, which might have less energy to take care of their own offspring which, in some cases are outright killed by the brood parasites. So the hosts have in turn evolved strategies for detecting and evicting any such parasites, which means cuckoos and cowbirds have also evolved methods of bypassing such defences.
This article discusses the fascinating details of this perpetual conflict between brood parasites and their hosts. It is a evolutionary tale of surveillance, deception, detection, aggression and countermeasures worthy of any spy drama.
Some birds wage perpetual war against each other, leaving countless numbers of victims
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Vidieo six
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2 Parasites, 1 Mosquito
I've written a new Parasite of the Day post! This one is about what happens when two different species of microsporidian parasites find themselves infecting the same mosquito host.
When two different parasites find themselves in a small host animal like a mosquito, there is only so much of the host to go around. So there is a pretty good chance that those co-occurring parasites are going to fight it out...
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Deadly Serenade
I've written a new Parasite of the Day post! This one is about a parasitoid fly and why the songs of male cicadas might bring them some unwanted attention. Emblemasoma erro is a parasitic fly that lays its maggot in the body of cicadas - my new post is about how they track down their prey and what the maggots do to their cicada host.
#scienceeveryday   #parasitology   #entomology  
During summer the air is filled with the rattling ruckus of cicada songs. Male cicadas produce this summer choir using a pair of noise-making organs located in their abdomen, with the aim of getting attention from any prospec...
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Fascinating - and something about that fly seems very familiar. I shall have to be on the lookout for references to similar parasitoids during the cicada season here in Japan.
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Scourge Of The Teredo
Earlier, I recorded an episode of Creepy but Curious - a regular radio segment on ABC New England that I go on every month to talk about weird and wonderful animals. This week, I talk about shipworms - a peculiar wood-eating mollusc that had plague wood structures at sea (that includes any wooden sailing ships) throughout human history. I talk a bit about its biology and what we can learn from the extraordinary partnership that it has formed with wood-digesting symbiotic bacteria.
#scienceeveryday   #marinelife   #mollusc  
These long, worm-shaped animals can be considered as termites of the sea - they will drill through any chunk of wood that is immersed in seawater and they are found all over the world
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Giant Arthropod And Its Tiny Prey
For the tl;dr crowd, back in the Ordovician period (between 485-443 million years ago), the sea was inhabited by 2 m-long, centipede-shaped arthropod that filtered the water for plankton.
I am a big fan of the anomalocaridid - or "Demon Cuttlecrabs". Most of the known anomalocaridid are active predators and I was quite excited when scientists discovered a filter-feeding anomalocaridid call Tamisiocaris borealis
- but that did not prepare me for Aegirocassis benmoulae - a 2 m long, centipede-shaped filter-feeder with a head-shield that looks like the front end of a cruise missile.
For more on this bizarre beast, follow the link below to read +Brian Switek's post on this amazing discovery.
Paleontologist Jakob Vinther pointed to a rust-colored boulder sitting on the black lab table. "What do you think that is?", he asked. I hadn't a clue. I was used to looking at bones - often really...
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Croc Country
In my first year zoology course, I try to get the student to realise "living fossil" is a bullshit term, and the idea that animals like crocodiles have been "unchanged for hundreds and millions of years" is utter dross cooked up by our limited perspective, having only existed on this planet for a fleeting moment.
Far from being "unchanged", the crocodilians we see today can be considered as a remnant of a much vaster array of different species which once existed. A recent discovery in Peru shows just how diverse crocodilians had been in the past. In the Amazon bonebeds, palaeontologists discovered at least 7 different species of crocodilians, all exploiting different ecological niches.
There's Purussaurus - a massive carnivore which grew to over 12 metres long and a bite force measured at about 69000 Newton (
Then there's Mourasuchus - a similarly-sized crocodilian which instead jaws shaped like that of a pelican (
And one of the new species discovered by this team was Gnatusuchus - a crocodilian with a shovel-like jaw, lined with short, globular teeth which indicates it probably crunched on shellfish.
Those species and more lived merely 10 or so million years ago in the Miocene. And before that, during the Mesozoic there was a bewildering array of crocodilians of all shapes and sizes living alongside the non-avian dinosaurs.
Crocodiles are not "living fossils" which have been "unchanged for millions of years" - we have merely label them as such due to our own ignorance and preconceptions.
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Evolutionary biologist, parasitologist
Parasitologist, Evolutionary Biologist, Researcher, Lecturer
Parasitologist and evolutionary biologist who also happen to write for a blog about parasites, and likes to draw things sometimes.

I am a biologist who conduct studies on various ecological and evolutionary biology aspects of parasitism/symbiosis. I also write for the Parasite of the Day blog, which I co-administrate with its founder, Susan Perkins of the American Natural History Museum.

Outside of my professional field, my favourite thing to do is drawing - some of which (but not all) are inspired by my scientific work. My drawings can be found on my dA account.
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