Editing Ancel Keys (section)

===Early physiology studies===

While doing fish research at Scripps, Keys would use statistical [[regression analysis|regressions]] to estimate the weight of fish from their length, at that time a pioneering use of [[biostatistics]].<ref name='Blackburn1998'>{{cite web |url=http://mbbnet.umn.edu/firsts/blackburn_h.html | title = Ancel Keys | access-date = February 5, 2011 | last = Blackburn, MD| first = Henry | year = 1998 | work = [[University of Minnesota]] | publisher = University of Minnesota}}</ref> Once in Copenhagen (1931), he continued to study fish physiology and developed techniques for gill [[perfusion]] that provided evidence that fish regulated their sodium by controlling chloride excretion through their gills.<ref name=Zadunaisky1969/><ref name='Keys1932'>{{cite journal | title = 'Chloride secreting cells' in the gills of fishes, with special reference to the common eel | first2 = EN | journal = The Journal of Physiology | last2 = Willmer | year = 1932 | first1 = Ancel | last1 = Keys | volume = 76 | issue = 3 | pages = 368–380| pmid = 16994355 | doi = 10.1113/jphysiol.1932.sp002932 | pmc = 1394694}}</ref><ref name='Keys1931'>{{cite journal | title = The determination of chlorides with the highest accuracy | journal = Z. Vergl. Physiol. | year = 1931 | first = Ancel | last = Keys | volume = 15 | issue = 2 | pages = 352–363| doi = 10.1007/BF00339114 | s2cid = 28971898 }}</ref> He would also use this perfusion method to study the effects of [[adrenaline]] and [[vasopressin]] ("pitressin") on gill fluid flow<ref name='BatemanKeys1932'>{{cite journal | doi = 10.2307/1537248 | title = Branchial Responses to Adrenaline and to Pitressin in the eel | journal = Biological Bulletin | year = 1932 | first = Ancel | last = Keys |author2=J.B. Bateman | volume = 63 | issue = 2 | pages = 327–336|url=http://www.biolbull.org/cgi/reprint/63/2/327.pdf | access-date = February 5, 2011| jstor = 1537248 }}</ref> and osmotic regulation in fishes.<ref name='Keys1933'>{{cite journal | title = The Mechanism of Adaptation to Varying Salinity in the Common Eel and the General Problem of Osmotic Regulation in Fishes | journal = Proceedings of the Royal Society B | year = 1933 | first = Ancel | last = Keys | volume = 112 | issue = 776 | pages = 184–199 | jstor=81638 | doi=10.1098/rspb.1933.0002| bibcode = 1933RSPSB.112..184K | doi-access =  }}</ref> He also designed an improved [[Kjeldahl method|Kjeldahl apparatus]], which improved upon Krogh's earlier design, and allowed for more rapid determination of nitrogen content in biological samples.<ref name='Keys1940'>{{cite journal | title = A Rapid Micro-Kjeldahl Method | journal = The Journal of Biological Chemistry | year = 1939 | first = Ancel | last = Keys | volume = 132 | pages = 181–187|url=http://www.jbc.org/content/132/1/181.short | access-date = February 5, 2011 | quote = A micro-Kjeldahl method is described. The method is more rapid than the ordinary macro-Kjeldahl procedure and is not appreciably less accurate | issue=1| doi = 10.1016/S0021-9258(18)73407-8 | doi-access = free }}</ref> This would prove useful for activities as diverse as determining the protein content in grasshopper eggs<ref>{{cite journal | doi = 10.2307/1537901 | title = Nitrogen content and distribution in eggs of Melanoplus differentialis during embryonic development | journal = Biological Bulletin | year = 1940 | first = Carolyn | last = Trowbridge |author2=Joseph Hall Bodine | volume = 79 | issue = 3 | pages = 452–458|url=http://www.biolbull.org/cgi/reprint/79/3/452.pdf | access-date = February 5, 2011| jstor = 1537901 }}</ref> and anemia in humans.<ref>{{cite journal | doi = 10.1172/JCI103087 | title = The anemia of liver disease: observations on its mechanism. | journal = Journal of Clinical Investigation | year = 1955 | first = James H. | last = Jandi | volume = 34 | issue = 3 | pages = 390–404| pmid = 14354009 | pmc = 438641}}</ref>

While at Harvard's Fatigue Laboratory, he was inspired by his Cambridge mentor [[Joseph Barcroft]]'s ascent to the top of [[Tenerife|Tenerife's]] highest peak and his subsequent reports. Keys wrote up a proposal for an expedition to the [[Andes]], suggesting the study could have practical value for Chilean miners who worked at high elevations.<ref name=Hoffman1979/> He was given the go-ahead and, in 1935, assembled a team to study the effects of high altitude on the body,<ref name=Sullivan2004/> such as how it affects blood pressure.<ref name=Brody2004/> He spent a couple of months at 9,500 feet (3,000 m.), and then five weeks at elevations of 15,000  to 20,000 feet (4,500 to 6,000 m.).<ref name=Hoffman1979/>

He noted there was no good way of predicting how well humans might [[High-altitude adaptation in humans|adapt to high altitude]], even if they adapted well to medium altitudes, a problem for potential pilots in a time before pressure control had become practical.<ref name='Keys1936'>{{cite journal | title = The Physiology of Life at High Altitudes | journal = The Scientific Monthly | year = 1936 | first = Ancel | last = Keys | volume = 43 | issue = 4 | pages = 289–312| jstor = 16163| bibcode = 1936SciMo..43..289K }}</ref> It was from these studies that he outlined the phenomenon of human physiological adaptation to environmental changes as a predictable event, a novel idea in a time when such parameters as blood pressure and resting heart-rate were considered immutable characteristics of individuals.<ref name=Kalm_2005>{{cite journal |vauthors=Kalm L, Semba R |title=They starved so that others be better fed: remembering Ancel Keys and the Minnesota experiment |journal=J Nutr |volume=135 |issue=6 |pages=1347–1352 |year=2005 |pmid=15930436|doi=10.1093/jn/135.6.1347 |doi-access=free }}</ref><ref name='Keys1938'>{{cite journal | doi = 10.1098/rspb.1938.0043 | title = Individual Variations in Ability to Acclimatize to High Altitude | journal = Proceedings of the Royal Society B | year = 1938 | first1 = Ancel | last1 = Keys | first2 = Bryan H. C. |last2=Matthews |first3=W. H. |last3=Forbes |first4=Ross A. |last4=McFarland | volume = 126 | issue = 842 | pages = 1–24| jstor=82153| bibcode = 1938RSPSB.126....1K | s2cid = 128707808 | doi-access =  }}</ref>