Networking in the Naughty Nineties

Group Portrait outside the Old Schools, Cambridge 1898
A. J. Allen Wellcome Collection CC BY 4.0

In August 1898 Cambridge hosted both the International Congress of Physiology and the International Congress of Zoology. The group portrait was no doubt taken on 25 August 1898 after conferment of honorary doctorates on the physiologists (Franklin 1938) as well as Haeckel and Hubrecht from the zoology meeting. The ceremony was at the Senate House adjacent to the Old Schools that forms the backdrop to the portrait. Franklin mentions the Vice-Chancellor Alex Hill is in the background (recognizable from the droopy mustache).

Those shown (left to right) are:

Étienne-Jules Marey (1830-1904) French cardiovascular physiologist also known for using chronophotography (a forerunner to cinematography) to study animals in motion. He collaborated with Anton Dohrn to document the movements of fishes.

Anton Dohrn (1840-1909) German entomologist and marine biologist who studied with Virchow, Haeckel and Gegenbauer at Jena. He was the founder and first director of the Zoological Station at Naples.

Camillo Golgi (1843-1926) Italian neuroscientist and biologist who also made a significant contribution to renal physiology. He discovered the Golgi apparatus a finding dismissed as an artefact by many contemporary scientists. He received the Nobel Prize in Physiology or Medicine 1906.

Ernst Haeckel (1834-1919) German zoologist whose work was hugely influential. His many interests included embryology and he famously argued that ontogeny recapitulates phylogeny.

Ambrosius Hubrecht (1853-1915) Dutch zoologist and embryologist. He described placentation in insectivores (sensu lato) and a major paper on the placentas of tree shrew and tarsier was published in the Proceedings of the Fourth International Congress of Zoology (pp. 343-411).

Wilhelm Kühne (1837-1900) German muscle and nerve physiologist. He also studied the physiology of digestion and coined the term "enzyme."

Henry Pickering Bowditch (1840-1911) American physiologist who was the founding President of the American Physiological Society and Dean of Harvard Medical School. He had worked beside E. J. Marey in Claude Bernard's lab in Paris and later with Carl Ludvig in Leipzig. 

Alexander Hill (1856-1929) Vice-Chancellor of University of Cambridge 1897-1899 had been Hunterian Professor at the Royal College of Surgeons. He was a lecturer in physiology and in addition to his ceremonial rôle was a scientific member of the physiology congress.

Hugo Kronecker (1839-1914) German muscle physiologist then at Berne, Switzerland. Like Bowditch he had worked under Carl Ludwig. 

Franklin KJ. A short history of the International Congresses of Physiologists. Ann Sci 1938; 3: 241-335 with 15 Plates. 

A colugo genome at last

Phylogenetic placement of colugos  (Scandentia) in the lineage of primates
From Mason et al. Sci Adv 2016 (here) CC BY-NC

Used to be that tree shrews (Scandentia) were regarded as the closest relatives to primates as cogently argued by Wilfrid Le Gros Clark. Molecular phylogenetics have brought that into question with some proposing colugos  or "flying lemurs" (Dermoptera) as a better alternative. But there have several competing hypotheses (see Martin). Choosing the right one has been difficult in the absence of a colugo genome.

Now that has been rectified in a comprehensive study by Mason and colleagues (here) who sequenced the genome of a Sunda colugo and compared it with genomes from 21 mammals. The result clearly came out in favour of colugos as the closest relatives to primates, supported by  20 shared indels and 16 shared retrotransposons.

There are many morphological similarities between tree shrews and colugos but the tree constructed by Mason et al. implies these are due to convergent evolution. Within Euarchontoglires they find tree shrews as the sister to Glires (rodents and lagomorphs).

Museomics and hidden biodiversity within colugos

Colugo fetus and placenta at term; ys = yolk sac;
pat = patagonium From Hubrecht 1894 (here)

Current reference works recognize no more than two species of colugo: Sunda Colugo (Galeopterus variegates) and the Phillipine Colugo (Cynocephalus volans). Mason et al. conclude that there may be as many as 6 Sundaic species and 2 Phillipine ones. They reached this conclusion by extracting DNA from museum specimens of known provenance. As an example, the Eastern and western populations on Borneo are highly divergent consistent with topographical features creating barriers to dispersal.

Currently we are re-examining the placenta and fetal membranes of colugos. We too have had to rely on museum specimens such as those collected by A.A.W. Hubrecht.

The importance of museum collections has been highlighted before in this blog. It is nice that scientists other than morphologists have discovered their value and coined the term museomics for studies of DNA from ancient specimens. Those in the current study ranged from 28 to 121 years old. The oldest specimen from the Raffles Museum of Biodiversity Research is contemporaneous with those collected by Hubrecht for his study of the fetal membranes and now housed at Museum für Naturkunde in Berlin. 

Emil Selenka

Emil Selenka (27 February 1842 - 21 January 1902

Emil Selenka died 113 years ago today, just before his 60th birthday. He was an eminent German zoologist, who spent much of his career studying the development of marine invertebrates, especially sea cucumbers. He turned to vertebrates rather late but made important contributions to the embryology and placentation of primates. His work on gibbons and orangutans is especially significant.

Pregnant uterus of Hylobates agilis (rafflei) showing the decidua

capsularis (d.c.) reproduced by Hill (here) from Selenka

I have shown this image before to document that gibbons resemble other great apes in having a decidua capsularis. Thus implantation is interstitial as it is in the human.

Fetus of Hylobates muelleri (Müller's Bornean Gibbon) and
uterus of Nomascus concolor (Black Crested Gibbon) from Selenka

In a moving tribute to Selenka, his pupil Hubrecht (previous post) wrote that his artistic talent was so great that it was almost a pity he became a professor of zoology rather than a painter.

Selenka amassed a large number of specimens and kept the skeletons as well as the reproductive tracts. He felt the maximum information should be gained from the animals that lost their lives. One recent study (here) estimates that Hubrecht may have bagged as many as 400 orangutans between 1892 and 1895.

Tempers ran hot over tarsiers

Philippine tarsier (Tarsius syrichta)
Jasper Greek Golangco

A recent post dealt with controversy over the evolution of placentals. This is nothing new. In 1897 debate ranged in the pages of Science about whether tarsiers belonged with lemuroid or anthropoid primates. It was sparked by the work of Hubrecht, who claimed that the embryological development of tarsiers resembled that of higher primates. He pointed to the precocious development of the extraembryonic mesoderm as well as the absence of an allantoic sac and its replacement by the connecting stalk.

Skull of Anaptomorphous

Had he stopped there all might have gone well. But Hubrecht proceeded to give a new interpretation of the primate fossil record, in particular Anaptomorphous homunculus (now placed in Omomyidae). This raised the ire of Charles Earle, curator of fossils at the American Museum of Natural History. He argued on the basis of osteological characters and dentition that tarsiers might represent an intermediate stage between lemuroids and anthropoids but certainly did not belong with the latter (here). In a spirited reply (here), Hubrecht wrote, "It is, indeed, rather hard upon me...to be now pilloried by Mr. Earle as if I had been making that coarse and indiscriminate use of placentary characters in classification against which I have been all the time loudly protesting."

In the next exchange (here), Earle argued for the superiority of palaeontological over embryological methods in determining phylogeny. He rather spoiled the effect by presaging one argument, "On this side of the Atlantic..."

As a footnote it is worth observing that there remain huge gaps in the fossil record of primates and the position of Anaptomorphous is still open to alternative interpretations. Meanwhile Hubrecht's view has triumphed over Earle's with primates split in Strepsirrhini (the lemuroids) and Haplorrhini (tarsiers and anthropoid primates).