Migration and Race Mixture from the Genetic Angle

Jul 7, 2026

The paper examines how immigration over the long term can reshape the genetic character of a population, treating growing societies as potential “melting-pots” that generate new combinations of physical traits and even temperament. Using principles of inheritance, it argues that humans share core chromosome structure and that differences arise from gene-unit variations. It discusses heterosis (hybrid vigour), blending and lumpy inheritance patterns, and the role of social and geographic “mating groups” that limit free gene mixing.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages5

Reading Time13 min

Migration and Race Mixture from the Genetic Angle

The Genetic Background

Mating Groups

SIR MACFARLANE BURNET O.M.,F.R.S.,Director,Walter and Eliza Hall Institute of Medical Research # Migration and Race Mixture fromthe Genetic Angle TROM THE LONG-TERM point of view,immi-Hgration is chiefly important to Australia 1for the overall changes that it will even-tually make in the genetic character of ourpopulation.Every growing country that receivessubstantial immigration from other parts ofthe world is in a sense a melting-pot from whichnew combinations of body-build,of skin colour,and even of personality,may eventually emerge.The process is immensely complex and canonly be described in broad outline.In many waysour description can be no more than an attemptto interpret the human observations in termsof genetic ideas that have been developed fromthe study of such very different animals asfruit flies and mice.Yet the very fact thatbasically similar gentic laws are evident in thebehaviour of mice,of fruit flies,and of bacteria,makes us confident that they are equally applic-able to man. ## The Genetic Background It may be desirable first to give a very briefrecapitulation of the facts of human inheritance.All human beings belong to a single speciesand healthy male and female individuals of anytwo races can produce healthy children who,in their turn,are fertile.In terms of the geneticmechanisms that are responsible for inheritance,this means that all human beings have the samenumber of chromosomes and that each chromo-some has a basic structure common to allhuman types.Differences between human beingsthat are not due to simple environmental *This paper was prepared at the request of the Depart-ment of Immigration for discussion by delegates at theAustralian Citizenship Convention.The views expressedin it are those of the author and do not necessarilyrepresent the official views of the Department. It is printed here by kind permission of the author. effects such as sunburn or scars,depend onthe existence of differences between the corre-sponding units at certain parts of one of thechromosomes.In one sense a chromosomeis like a string of beads and when mating occursmale and female chromosomes temporarilyunite,bead for bead.The rules by which theunits which we call genes in the double stringof beads are derived from one or other parentand are duplicated and redistributed to off-spring can be found in any textbook of geneticsand need not be described here.All that needsto be said is that any given human chromosomecan be equated in detail to the correspondingchromosome in any other human being.Nomatter how extreme the difference between theparents,Nature can see to it that a self-consistenthealthy offspring will result.In a rough sort ofway,every visible difference,e.g.in skin colouror hair texture,will depend on one,two ormore unitary differences between parentalgenetic units.A child will receive the unitswhich make up his chromosomes,one fromeach parent,and it is the interaction of thesepairs of genes which will determine the character-istics of the child. One of the most important genetic processesoccurring in the course of race mixture isheterosis or hybrid vigour.In very simplifiedand not quite accurate form,one can vizualisethis as resulting when there are very many genedifferences in each corresponding pair ofchromosomes.In general,the body tends todevelop according to the pattern of the “better”of each pair of dissimilar genes and with so manychoices available the overall result is likely tobe better than when each parent contributesmany similar mediocre genes.This is a positiveadvantage of hybridization to which may be added the related potentiality of new genecombinations providing on occasions an indi-vidual with exceptionally valuable new character-istics.And sometimes,of course,we mustalso expect exceptional but undesirable charac-teristics. For most of the qualities,like height,strengthand intelligence,which are socially important,as well as for others like skin colour and bodybuild,it is clo

FAQs

How does the paper connect immigration to changes in a population’s genetics over time?

It argues that sustained immigration acts like a melting-pot, producing new gene combinations that can alter the population’s genetic character in the long run.

What basic genetic premise does the paper use to explain inheritance across races?

It states that all humans belong to one species, share the same chromosome number, and that differences among people come from variations in corresponding gene units along chromosomes.

What is heterosis (hybrid vigour), and how is it described here?

The paper describes heterosis as an advantage arising when many genetic differences exist between paired chromosomes, leading to overall traits that may be better than when parents contribute similar gene variants.

Why does gene mixing not occur freely in real societies, according to the paper?

Gene mixing is limited by social, racial, and geographic barriers that create “mating groups,” where mixing is relatively free within groups but restricted between them.

Jul 7, 2026

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