Genetic
inheritance
Which gene is responsible for the inheritance of toe
and fingerprints? The Genome study announced in February 2001 that
there are only about 30,000 human genes responsible for our inheritance,
not 100,000 as was previously predicted. The remaining 70,000 are
relics of our evolutionary past, dubbed in U.S. colloquialism, 'junk
genes'. The maximum difference in human D.N.A.
is only 0.5% [about 15,000 CGTA units] there would be even less between members
of a shared family name.
Surnames are far more resilient than genetics
As each generation passes, the number of chromosomes inherited from a
particular individual is reduced by half whilst the number of predecessors
doubles. As a consequence, the number of genes is also halved from any specific
parent. The reduction occurs like this:
| Generation |
No. of genes |
No. of predecessors |
| Parent |
30,000 |
- |
| F 1 |
15,000 |
2 |
| 2 |
7500 |
4 |
| 3 |
3750 |
8 |
| 4 |
1875 |
16 |
| 5 |
~938 |
32 |
| 6 |
~469 |
128 |
| 7 |
~234 |
256 |
| 8 |
~117 |
512 |
| 9 |
~59 |
3584 |
| 10 |
~29 |
7168 |
| 11 |
~15 |
14336 |
| 12 |
~7 |
28672 |
| 13 |
~4 |
57344 |
| 14 |
~2 |
114688 |
| 15 |
~1 |
229376 |
| 16 |
- |
458752 |
Thus for any specific predecessor, after 10 generations [or about 250 years]
approximately 29 genes remain from that particular person [obviously the
remainder of the chromosomes are composed of genes from the multitudes of
other predecessors]. Thus although we may see that we are descended from a
particular person, most of the genetic change or loss has occured in the first
few generations so that by the 15th generation [~ 400 years] there is actually
very little genetic material remaining [< 3.33 x 10-4 %] from
the specific predecessor. At the same time we are seen by positive exponential
growth to be descended from almost a quarter of a million predecessors. Certainly,
an inherited surname possesses a much longer 'shelf- life' than the genetic
material from a single predecessor. We are indeed unique and composed of
the genetics of many persons who have gone before and will with luck, follow
us. That is the much sought after 'everlasting life', we already have it.
| Today: Life expectancy in Western Societies averages 76 times around the sun for males and 82 for females. 75% of centenarians are women. |
Martha Meakin [nee Midgley] of Normanton, West Yorkshire is the oldest
Midgley at 104 years [2001] whom I have become aware of, can anyone
substantiate a longer lived Midgley?
Contact: Tim Midgley
We know there are many traits and even diseases which "run in families". Studies at the University of Newcasle, N.S.W. have indicated that a person's intelligence can be the result of a gene carried on the female X chromosome.
Males possess a mixture of X & Y chromosomes as the 23rd pair (sex
chromosomes) whereas females have a pair of XX chromosomes. This
indicates that when a male inherits intelligence, if his mother passes
this on from his grandmother then he is likely to have the grandmother's
intelligence gene.
The mother may not have the phenotype for her mother because
she is also carrying the second X chromosome which may positively
or negatively reinforce the the gene in the first X chromosome inherited.
Males have a slightly higher chance of having intelligences from the
extremes of the distribution curve because they only inherit one X chromosome.
This conforms to known distributions of I.Q. for males and females
which shows more males having very high and very low I.Q's compared
to females, but more females outperform males in the mid-range. Gentlemen,
before you procreate check the intelligence of your mother-in-law!
Like males, females can still get very low and very high I.Q's but there are fewer at the extremes of the distribution curve compared to the average male.
From a study of twins it appears that I.Q. is about 80% nature and 20%
nurture. The late Prof. Max Eysenck (L.S.E.) strongly argued for
a genetic basis to human personality and behaviour but his work was
seen as highly contentious. We can inherit haemophilia, a sex linked
blood disease carried on the female chromosome which only affects males,
so we may ask the question why do we revile from inheritance of intelligence?
Is it that I.Q. is not seen as a tangible entity but a human concept
and very limited in what it measures?
Recent genome studies indicate this
hypothesis is now much maligned, it appears that intelligence (as measured
by I.Q.) is a result of a combination of genes.
There are now considered to be multiple intelligences such as
:
numerical
spatial
language
musical
visual
auditory [some people are good listeners]
interpersonal relationships
intrapersonal relationships
kinesthenic [learning through moving or doing]
calisthenics (e.g. dancers, wood turners)
Intelligence Quotient tests tend only to examine the first three "intelligences"
and hence its demise as a tool of measurement in education. This
fits better with the "Outcomes" approach to education where students
are recognised to have specific abilities. These intelligences are likely
to be carried in families and again a gene or group of genes may
be responsible, if they are sex linked then this would give genealogists
something else to think about.
The human genome project which mapped 3.1 billion
CGTA combinations
was essentially completed a few years ago, this search provided us
with more information about what our real inheritance is. Reports in November
1999 indicated that a U.S. commercial company trying to make monetary
gain by identifying the human genetic code with the aid of a super-computer
gene sequencer, claimed it could achieve in less or the same time what
the U.S.-U.K. genome project would achieve. The difficulty appears to
be that it would not seem possible to patent parts of the human genetic
code even though it was not invented by anyone or any group. The written
CGTA code was like
a book published in a hurry, there were "spelling mistakes" in the
code and "pages" were missing. In 2001 the "slower" but more complete
method of uncovering the human genome was jointly announced alongside
the commercial venture, by William Clinton in the White House.
Some believe genetic inheritance is eternal life, "The meaning of life"
as we each live on through our genes, whilst the $10 worth of
chemicals we have borrowed for 70 years is used to transiently hold
those genetic codes and is recyled through ecologial systems. Isn't life
clever! An island of order in a sea of chaos.
| Key: X =female sex chromosome -chromosome carrying gene for intelligence (I.Q.) Y= male sex chromosome |
First family (F2) :
X1X2, X1X3, Y1X2, Y1X3
we can see here that the male Y1X3 mix is carrying only the intelligence gene in the X3 chromosome whilst the female X1X3 carries a mix of intelligence genes from the father's mother and the mother's mother.
In the next sequence notice how the female X chromosome brings other genetic material to the male, it appears that the female chromosome brings variety to an unchanging male Y chromosome (supposing no mutations occur).
P1: X1Y1 x X2X3
P2: X1Y1 x X4X5
F2: X1X4, X1X5, X4Y1, X5Y1.
P3: X5Y1 x X6X7
F3: X5X6, X5X7, X6Y1, X7Y1
If the children do well it must be genetic,
if they don't, it must be their teachers!
| DNA
clues at scene can name criminals/families
DNA found at a rape or murder scene could soon be used by police
to trace the surname of the criminal. He said it meant most families had a single founder whose Y chromosome pattern had still survived. "If you have a more common name, such as Smith or Jones you might find several founders, but most people have relatively rare surnames and I suspect for them there is only a single founder." The discovery, published in this month's issue of the American Journal
Human Genetics, was so significant it was already the subject
of a worldwide patent. |
Mitochondrial D.N.A. and gene mapping:
Oxford Ancestors#- A commercial site where you
can have your D.N.A. mapped, by Prof. Bryan Sykes' team to find out
:
1. if you have Viking ancestry
2. if you belong to the same Midgley branch as someone else
[by comparing your profiles]
3. which of the "Seven daughters' of Eve" you are related to!
Prof.
Bryan Sykes' family tree is crossed with some of the Midgley branches
in West Yorkshire.
Genetic "fingerprint" analysis was first developed
by Alec Jefferys in 1984 researching in the Biology Department at
the University of Leicester,
U.K. Initially called "DNA fingerprinting" we now refer the separation
of DNA proteins by elecrophoresis and the identification process as
"DNA profiling". "On the morning of the 10th September 1984 Alec Jeffreys
stumbled upon DNA profiling, identifying the patterns of genetic material
that are unique to almost every individual. The discovery revolutionized
everything from criminal investigations to family law. Jeffreys is
still awed, and a bit worried, by the power of the technology he unleashed
upon the world. “I think there are potentially major issues about genetic
privacy,” Jeffreys said in September 2004 at a press briefing to mark
the 20th anniversary of the discovery.
In the November 1999 issue of Science the Whitehead Institute in Massachusetts sets out the case for the diminishing Y chromosome. The institute traced the divergence of the X and Y chromosome.The earliest, and todays simplest plants and animals show no male/female characteristics. This divergence began about 320-240 million years ago and is continuing today.
Like many genetic changes it began with a random mutation on the proto-Y
chromosome which continued with punctuated evolution ("jumps") until
today.
The modern X chromosome has about 10 times more genes than
a modern Y chromosome which has been casting off genes that are not
useful to the male for the last 320 m.y.
Each Y contains the SRY gene which is the master-switch
for maleness in all plants and animals which reproduce by sexual methods,
i.e. two distinct specialised reproductive cells.
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