Dr. L. Cavalli-Sforza
18, Via Fatebenesorel le
Milan, Italy

Dear Luca: |
My reply to your tape (which was quite clear) must have crossed your letter

of April 2h. To reassure you, let me be even more explicit, even If repiti-
tlous.

1. We can undertake Howard's support (assuming that Norm will confirm his
approval of Howard's extended leave; he was not so pleased about that
a few months ago). { propose to reappoint him under our Genetics
training grent, effective June 30, 1963, so as to use some balances
In our current year. He should sign the enclosed forms and make his
own arrangements sbout terminating his other support. The checks
will come monthly, essentially In advance, direct from Stanford.

{

2. | would be very pleased to cooperate In your grant proposal. See en«
closure, to which you should furnish address.

| have been almost out of comalssion this last month, between writing con-
puter programs and lacking my good secretary. But we have also been converting
everything In sight to machine systems and this begins to show some signs of
diminishing the total chaos.

The PDP computer has arrived, and with Its display scope Is a charming play-
thing. We are setting up keyboard connection to it (at the Comp Center) fran
the Department. We have elso been successful In winning a ‘LINC’ computer
for our own local use, part of an NIH evaluation. This Is a small machine,
only 1000 word memory, but with excellent analog input/output features. It
may be especially useful as a terminal station for connection to the POP -
7090 (BM compiles.

As ever,

Joshua Lederberg
Professor of Genetics
Kay 10, 1963

P.$.

Luca ~ | am worrled thet stratification with respect to ABO has been
grossly underestimated, and may lead to gross blas In tests for selection.
introgression between groups is likely to be sax-dependent; "hybrid' matings
In any case will be atypical tn many respects other than Inherent fertility,
which can lead to spurious attributions of incompatibility. Have you any
chance to look at the distributions of ABO rating types for spouse-to-spouse

correlation i mt of offspring?

Why not also stress this in your NATO proposal, a/c Its relevance to the
consequences of Internationa! migration?
We have recently been studying the seasons! variation of birth incidence
In the United States, with reference also to Its impact on the Incidence
of neonatal disease and of mantal retardation. Over all, the cyclic
swing In the United States Is about 10% from the mean expectation, with

@ peak In September and a trough In May. Many factors Influence the
details of the speetrus, Including maternal! age, the father's occupational
stratum, color, end the general geographic region. However, these effects
are rather small compared to the striking differences between the North
American and the Eurepean data. With some varletion from country to
country. European births show a striking peak In the spring and grough In
the fall.

Although some statistics are available, the matter has never been studled
In any detail. further comparisons of the seasonal variation of healthy
and of diseased births, with respect to the factors avaliable In each
country's data, may throw further light on the actual mechanisas of the
cycles (about which there can be easier speculation than proof et the
present time) and on thelr fmpact on child health, especislly prematurity,
which Is dependent on season In the United States.

Of special Interest will be the reproductive behavior of Immigrant graups
(especially In the United States) compsred to the patterns In the country
of origin.