page_title: Great Hippocampus Question
section_title: Man's Place in Nature
hierarchical_section_title: Great Hippocampus Question / Man's Place in Nature
caption_attribution_description: Deutsch: Seitenansicht eines deformierten und eines normalen Schimpansengehirnes.
context_page_description: The Great Hippocampus Question was a 19th-century scientific controversy about the anatomy of apes and human uniqueness. The dispute between Thomas Henry Huxley and Richard Owen became central to the scientific debate on human evolution that followed Charles Darwin's publication of On the Origin of Species. The name comes from the title of a satire the Reverend Charles Kingsley wrote about the arguments, which in modified form appeared as "the great hippopotamus test" in Kingsley's 1863 book for children, The Water-Babies, A Fairy Tale for a Land Baby. Together with other humorous skits on the topic, this helped to spread and popularise Darwin's ideas on evolution.
  The key point that Owen asserted was that only humans had part of the brain then known as the hippocampus minor, and that this gave us our unique abilities. Careful dissection eventually showed that apes and monkeys also have a hippocampus minor.
context_section_description: Huxley expanded his lectures for working men into a book titled Evidence as to Man's Place in Nature, published in 1863. His intention was expressed in a letter to Charles Lyell which referred to the Monkeyana poem of 1861: "I do not think you will find room to complain of any want of distinctness in my definition of Owen's position touching the Hippocampus question. I mean to give the whole history of the business in a note, so that the paraphrase of Sir Ph. Egerton's line 'To which Huxley replies that Owen he lies', shall be unmistakable." Darwin exclaimed, "Hurrah the monkey book has come". A central part of the book provides a step by step explanation suitable for newcomers to anatomy of how the brains of apes and humans are fundamentally similar, with particular reference to both having a posterior lobe, a posterior horn, and a hippocampus minor. The chapter concludes that this close similarity between apes and mankind proves that the original definition by Linnaeus of the biological Order of Primates was correct to include both, and mentions that an explanation of humans originating from apes is provided by Darwin's theory. The book also includes six pages of small print giving "a succinct History of the Controversy respecting the Cerebral Structure of Man and the Apes" describing how Owen had "suppressed" and denied what Huxley had now shown to be the truth regarding the hippocampus minor, posterior horn, and posterior lobe, describing this as reflecting on Owen's "personal veracity". Reviewers regarded the book as a polemic against Owen, and a majority of them sided with Huxley.
  Sir Charles Lyell's authoritative Geological Evidences of the Antiquity of Man was also published in 1863, and included a detailed review of the hippocampus question which gave solid and unambiguous support to Huxley's arguments. In an attempt to refute Lyell's judgement, Owen again defended his classification scheme, introducing a new claim that the hippocampus minor was virtually absent in an "idiot". Then in 1866 Owen's book On the Anatomy of Vertebrates presented accurate brain illustrations. In a long footnote, Owen cited himself and the earlier literature to admit at last that in apes "all the homologous parts of the human cerebral organ exist". However, he still believed that this did not invalidate his classification of man in a separate subclass. He now claimed that the structures concerned – the posterior lobe, the posterior horn, and the hippocampus minor – were in apes only "under modified form and low grades of development". He accused Huxley and his allies of making "puerile", "ridiculous" and "disgraceful" attacks on his scheme of classification.
  The publicity surrounding the affair tarnished Owen's reputation. While Owen had a laudable aim of finding an objective way of defining the uniqueness of humanity and distinguishing their brain anatomy in a qualitative way, not just a quantitative way, his obstinacy in refusing to admit his errors in trying to find that difference led to his fall from the pinnacle of British science. Huxley gained influence, and his X Club of like minded scientists used the journal Nature to promote evolution and naturalism, shaping much of late Victorian science. Even many of his supporters, including Charles Lyell and Alfred Russel Wallace, thought that though humans shared a common ancestor with apes, the higher mental faculties could not have evolved through a purely material process. Darwin published his own explanation in 1871 in the Descent of Man.
caption: Lyell's book included an illustration showing the distorted image of a chimpanzee brain used by Owen, and a correct view by another anatomist showing the projection of the occipital lobe at the rear which Owen said was not present in apes.
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