Lecture 1 ‘The genomic basis for the evolution of human traits’ Flashcards
Encephalization quotient (EQ) or encephalization level
is a relative brain size measure that is defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size: brain-to-body index.
most dramatically changed part of the brain
The neocortex, the part of our brain which we use to talk, think, and create
Expansion of the neuronal progenitor pool on different levels
And how much are progenitors dividing in mouse and human?
two levels in mice, Radial Glial Cells and Intermediate Progenitors.
In the primate brain, intermediate progenitors can divide up to 8 times humans before becoming neurons. The Primate neocortex exhibits an expanded proliferative compartment in the outer subventricular zone (OSVZ)
Why is it important to know about anatomical evolutionary differences? For example the size of human brain
- Subtle changes in progenitor proliferation kinetics can have huge size-consequences
- Lots of genes involved in progenitor cell division are associated with brain disorders that lead to a small brain (microcephaly)
- Small changes in gene expression in neuronal progenitor cells can have dramatic effects on brain size
For, for example brain size, why can we not just look at the genes which are essential for neural development and have undergone evolutionary changes?
The genes will not look that different from each other, it are the changes in gene regulation, rather then the genes themselves, are likely to account for the majority of biological differences between spiecies.
Human-specific DNA
the parts of the genome where we are unable to find ortholous regions for in the other spieces
Segmental duplications and retroviral DNA elements are also pieces of the human genome which are not find back in for example the chimpanzee
4 levels of genomic evoluation
1) Changes in the coding part of genes
- Selection of positive mutations, example of FOX2
2) Changes in how genes are regulated
- Regulatory mutations
- Increased complexity of gene regulatory networks
3) Changes in (epi)genomic environment?
4) Creation of new genes / deletion of existing genes
How can diseases help in a better understanding of evolutionairy genes?
The human brain is dramatically increasing, in case of microcephaly the brain size is much smaller. By comparing the genes from a patient vs a healty human you can determine the differences and predict which genes are involved in causing the dramatically increase in human brain size.
