 |
The question of "What makes us human?" has been pondered by philosophers and others since time immemorial. The answer is usually implied in the charateristics of humans. We can draw up a list of differences: bodily differences such as the plantigrade (flat to the floor) foot, opposable thumbs, bipedal gait and big brains; mental differences in intelligence, speech, imagination, tool manufacture and use, fire and cooking; and social differences in culture, religion, music, art, reason, use of
|
Figure 10-34a Human and other Primates [view large image] |
medicine, social learning and the formation of social groups. Such list would separate us more or less from the other animals (Figure 10-34a). Table 10-05 lists some different characteristics between human and other species. |
Characteristics |
Other Species |
Human |
Function(s) |
Cooperation |
Few |
Common in human societies |
Better chance of success in difficult tasks |
Science |
No |
Involving abstract concept |
Study of the material world |
Etiquette |
Unknown |
Manners in social contact |
Keep microbes away from each other to show good will |
Play |
Limited |
Devoting lot of time and involving many friends |
Learning and social development |
Rules |
Pecking Order |
Set of rules for members in a society |
Maintenance of stable society |
Monogamousness |
< 10% |
Most common mating arrangement |
Reduce efforts in keeping the dominant position |
Intercourse |
Open copulation |
In privacy |
Hiding infidelity |
Gossip |
Grooming |
Grooming with language |
Maintenance of personal relationship |
Gene |
Mutation in Human |
Function |
AMY1 |
More copies |
Digestion of starch |
ASPM |
Several bursts of change |
Brain size |
DARC |
Single point mutation on "Duffy Antigen Receptor" |
Suppress expression of DUFFY to block malaria infection |
DUF1220 |
Lot of duplicated copies |
High cognitive function |
EDAR |
EDAR Single nucleotide polymorphism (SNP) |
Straight black hair |
FOXP2 |
In 2 locations of the amino-acid sequence |
Speech and Language |
HAR1 |
Substantial change |
Fetal brain tissue development |
HAR2 |
Second most changes (after HAR1) |
Wrist and thumb development |
LCT |
Mutation on chromosome 2 |
Digestion of milk sugar in adulthood |
MYH16 |
Tiny mutation |
Affecting jaw muscle leading to smaller jaw |
SLC24A5 |
Different versions in exons of the SLC24A5 gene |
Difference in skin colour |
TRIM5 |
Single base change |
For combating the PtERV1 virus |
 |
some 3% to 4% of the genome and mostly embedded within and around the genes, is crucial. It seems to govern a lot of what we actually see. A new study has found the strongest evidence yet in the brain's right prefrontal cortex that sets humans apart from other primates. This is the site where we understand the mental processes of others - the basis of our socialization and what makes us human. It gives rise to our capacity to feel empathy, sympathy, understand humor and when others are being ironic, sarcastic or even deceptive. It is the cumulative result of 300,000 years of tool-making evolution, which requires the ordering of sequences and the hierarchical assembly of the same components into different configurations (to make tools of different functions). As makers of single-component tools, we progressed at a remarkably slow pace starting about 2.5 million years ago. But with the appearance of composite tools, near-modern brain size anatomy and perhaps of grammatical language 300,000 years ago, the pace quickened exponentially.
|
Figure 10-35a Human-like Consciousness in Other Animals [view large image] |
We became long-range planners and grammatical speakers. Eventually, we possess all the prefrontal capacities - working memory, our sense of self, and theorizing about other people's minds. The so-called intentionality now constitutes the essential ingredient for the new definition of humans. However, it is still not completely distinctive. Human children cannot distinguish between their own intentions and those |
of others until the age of four. Such ability develops gradually over the years, continuing well into adolescence. It is known that some parts of the brain are still developing in that age. They are responsible for many problems associated with
Time (MYA) |
Riddle |
Tentative Explanation(s) |
6 (last common ancestor) |
There's only 1% difference between the genomes of humans and chimps |
Difference in gene expressions with culture feed back loop (to be discovered) |
~ 4.2 (FA), 1.7 (descending to savannah) |
Transition to bipedal requires anatomical changes and clumsy trial period |
Package of advantages including freed hands to perform tasks, long distant traveling, ... |
2.6 - 0.5 |
It took a long time for technological advance from stone flakes to hand axes |
The development requires bigger brain and more complicated neural connections |
~ 2 |
Evolution to a big brain, which consumes a lot of energy |
Single mutation weakened the jaw muscles, which constrained the growth of the brain |
1.6 - 0.6 |
It is not known exactly when did language evolve |
The quoted time interval is between the appearance of neural connections in chest/diaphragm and change in voice box |
~ 0.2 |
Humans shed hair which is so useful for insulation by all mammals |
A possibility is to get rid of parasites (harboring in fur) that spread disease |
1.8 (1st wave) - 0.065 (3rd wave) |
The cause(s) of global migration from Africa |
Overcrowding in the Horn of Africa pushed our ancestors to look for living space |
0.024 |
Who or what is responsible for the extinction of Neanderthals? |
Finger points to the crime of H. Sapiens, but it could be climate change as well. |