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PubMed1976

Structural variability of human chromosome 9 in relation to its evolution.

Human chromosome 9 shows a high susceptibility for structural rearrangements, particularly pericentric inversions, which often are transmitted. Three types of pericentric inversions can be observed on No. 9: 1) Type I, showing the total constitutive heterochromatin in the short arm. 2) Type II with part of the C heterochromatin on the short arm, the rest located on the long arm proximal to the centromere. 3) Type III: a subtelocentric chromosome with part of the C heterochromatin in the very short arm and the rest located interstitially on the long arm. With these inversions as well as with other structural rearrangements, e.g. translocations, the break-points are located preferentially within the C heterochromatin or close to the heterochromatic-euchromatic junctions. These findings are in contrast to the findings in lymphocytes from 5 patients with fancomi's and after irradiation in vitro, reported in the literature. In lymphocytes break-points seem to be distributed more or less by chance. These observations together led us to speculate that human chromosome 9 primarily was an acrocentric chrosome; in morphology and at least in some functions similar to D- and G-group chromosomes. During evolution this acrocentric chromsome changed to a submetacentric one due to a pericentric inversion.

Animals↗
PubMed1979

Lymphoma development in mice and humans: diversity of initiation is followed by convergent cytogenetic evolution.

Human B cell lymphoma and murine T cell leukemia can be initiated by several agents. The present paper formulates some thoughts on the role of cytogenetic changes in the subsequent neoplastic process. Initiation creates long-lived preneoplastic cells. In some respects, they are comparable to in vitro-transformed ("immortalized") cell lines that maintain a diploid karyotype and are not tumorigenic in vivo. The development of a tumorigenic ("autonomous") clone is dependent on additional changes at the genetic level. In human B and murine T cell lymphoma, there are characteristic nonrandom chromosomal changes. The 14q+ marker appears to play a key role in human B cell lymphomas. The reciprocal 8;14 translocation in Burkitt lymphoma is a specialized subclass within this category. In murine T cell leukemia, trisomy 15 is the predominant change. The clustering of these nonrandom changes to tumors derived from a certain cell type rather than to tumors induced by a given etiological agent has important implications for the understanding of the genetic control of cellular responsiveness to growth-regulating forces in vivo.

AKR murine leukemia virus↗
PubMed1992

The hu-PBL-SCID mouse model. Long-term human serologic evolution associated with the xenogeneic transfer of human peripheral blood leukocytes into SCID mice.

We present a 2-year serologic analysis of severe combined immune deficiency (SCID) mice populated with human peripheral blood leukocytes (PBL, hu-PBL-SCID mice). After 10-20 x 10(6) PBL transfer, human IgG serum levels generally increased in the SCID mouse recipient for 2 months, and thereafter decreased without returning to zero for at least 2 years. Great variability existed between different hu-PBL-SCID mice with regard to Ig serum levels even when derived from the same donor's PBL aliquot. The ratio of IgM to IgG serum levels was lower in hu-PBL-SCID mice than in the donors. The half-life of human IgG in the SCID mouse is shorter than in the human (8 days vs 23 days), suggesting a much higher production of IgG than expected from serum levels. The majority of hu-PBL-SCID mouse sera analyzed by high resolution electrophoresis had a smear appearance suggestive of diverse human Ig, generally with superimposed multiple faint mIg. Few mice developed strong human mIg, associated with lymphoproliferative diseases. In the hu-PBL-SCID mouse model, the transfer of cells from donors making antibody with defined specificity against TT and nuclear antigen resulted in the appearance of these antibodies in only a minority of the recipients.

Animals↗
PubMed1979

Evolution of human longevity: a critical overview.

Evolution of longevity of the ungulates, carnivores and primates is reviewed. Special emphasis is focused on recent evolutionary history of longevity along the hominid ancestral-descendant sequence leading to modern man. Maximum life span potential (MLP) or the change in MLP is predicted in extinct species by (1) a phylogenetic analysis of the MLP of present living species and (2) an empirical equation using brain and body weight estimates from fossils. Both of these methods indicate MLP generally increased during mammalian evolution and at an extremely fast rate during the appearance of the hominid species. These results suggest that relatively few genetic alterations were necessary during the recent evolutionary history of man to significantly extend his innate ability to maintain mental and physical health. Much evidence indicates these genetic alterations principally involve regulatory genes, which control a conserved set of structural genes. Evolution of longevity in man could therefore be a result of simple changes in temporal and quantitative expression. Whether these genetic alterations result from mutational changes and/or chromosomal rearrangement cannot yet be evaluated.

Aging↗
PubMed1977

Ethology and man: science or myth?

What is known of human evolution gives us little help in describing the biological nature of man: even our fossil history is obscure, and most statements on the evolution of human behaviour are guesses. The fact that primitive man was a predator on other species does not signify that man is "naturally aggressive" to his own kind. The notion of an inherent drive to aggression has no scientific foundation. Knowledge of the conduct of other species can lead to no valid conclusions about human behaviour. The same limitations apply to interpretations of modern man based on what is known of human hunter-gatherers. Ethology can contribute to human studies (1) by providing methods of observing and analysing behaviour, and (2) by providing hypotheses that can be tested. Zoologically-based hypotheses on the ill effects of crowding have been useful but have proved to be wrong. Others on the effects of stimulation in early life, and on breast-feeding and milk composition, have been more fruitful. Abnormal conduct, such as that of Kanner's syndrome, can be usefully studied by ethological methods. Man is a learner and a teacher, whose knowledge of himself increases slowly with the growth of critical research.

Aggression↗
PubMed1976

Auditory perception and speech evolution.

Human speech perception seems to involve the ability to recognize groupings of speech sounds rather than component phonemes, and to distinguish between permuted orders of items within sequences as holistic entities. Humans can use this Holistic Pattern Recognition (HPR) not only with speech and music, but also with sequences of arbitrarily selected sounds after very little practice. Infrahuman primates, cats, chinchillas, and birds also seem to employ HPR with auditory sequences. Further, there is recent evidence that animals unable to produce speech sounds can nevertheless discriminate between closely related phonemes. Thus, it appears that human speech perception employs prelinguistic abilities shared with other animals to distinguish between phonemic groupings. Of course, use of speech for communication also requires establishment of phonemic groupings as symbols, and sequential arrangement of these symbols, by rule, to convey the desired message. Identification of Components and their Order (ICO) for auditory sequences is limited to humans. ICO involves verbal categorization and storage of the names for successive auditory items as they appear, followed by retrieval or the names in the order stored. Thus, direct identification of the order of sounds within auditory sequences rests upon verbal ability, which provides an explanation for the difficulty that aphasics have in identifying order within nonverbal sequences. Much confusion in the literature on auditory sequence perception seems to have resulted from a failure to differentiate between HPR and ICO.

Animals↗
PubMed1976

The role of neurosis in phylogenetic adaptation, with particular reference to early man.

The author hypothesizes that neurosis results from maladaptation and leads to further maladaptation, thus creating a vicious cycle that can be viewed as having played a significant role in human evolution. Individuals who were less successful in the struggle for survival during prehistory would have been more likely to become neurotic, a maladaptation that would magnify existing genetically transmitted differences in their viability and affect both the choice of a mate and the viability of their offspring. This process would have accelerated human evolution by favoring the most viable. The author relates this theory to his concepts of assortative mating and to other theories of the role of neurosis.

Adaptation, Psychological↗
PubMed1992

Genetic variation and evolution of human parainfluenza virus type 1 hemagglutinin neuraminidase: analysis of 12 clinical isolates.

The extent of genetic variation and evolution in a population of human parainfluenza virus type 1 was investigated. The hemagglutinin neuraminidase genes of 13 isolates collected over a 26-year period were sequenced and compared. All isolates except the 1957 type strain were from a single geographic location and demonstrated significant consistent genetic change from the type strain (47/7 [nucleotide/amino acid] substitutions). Antigenic subgroup A isolates demonstrated minor intragroup differences (9/1 substitutions). However, 18/7 unique substitutions separated subgroup A from B regardless of geographic location or year of isolation. Multiple strains of both subgroups appeared and reappeared over decades with only minor variation. There may be significant genetic differences between clinical isolates based on geographic location, and progressive mutational change may occur. Previously defined antigenic and now genetic subgroups were stable and at least regional in distribution over the period studied. The biologic implications and extent of this variation need further evaluation.

Animals↗
PubMed1979

Polygamy and the evolution of human longevity.

An alternative to previous explanations of the rapid increase in man's longevity and intelligence during the several million years of his recent evolution from pre-hominid, clearly shorter-lived and less intelligent, primate ancestors is presented. The general thesis is that a very greatly accelerated rate of incorporation of favorable genes or gene combinations can be achieved in surprisingly few generations among social animals provided that dominant males become the patriarchs of many descendents by virtue of their partial or complete monopoly on available females. The conclusion is that man probably differs from his ancesters of 0.5 to 5 million years ago by many thousands of genes (both structural and regulatory) rather than the dozens or few hundreds that have been postulated on the basis of more classical treatments of selection pressures, gene frequency changes and mutation rates. The concepts developed here formally apply only to two alternative alleles, rather than to groups of genes which segregate independently, or to characters determined by multiple alleles. The appropriate mathematical treatment of the latter real situation is not readily visualized; nor is account taken of the likelihood that different tribes of pre-humans developed different specializations via the above mechanisms which were then (later) combined into an emerging human stock through matings between members of different tribes. The very great variability both in longevity and in intelligence between different races of animals such as dogs, which have been the objects of deliberate genetic selection by humans for particular heritable traits, may parallel our own recent history, even though the selection mechanism (deliberate human selection vs. polygamous dominance) is quite different in the two cases. The onset of civilizations consisting of amalgums between smaller, previously competing tribes, together with the humanitarian responsibilities to each other we share as a species, ironically has probably arrested further evolution of human longevity (and perhaps of intelligence) in the modern world. Possibly even retrogressive changes are occurring, except in those rare sub-populations in which special social and cultural practices tend to favor selective perpetuation of characteristics which are usually viewed as beneficial.

Alleles↗