and finally...
​  to ask why...how...when...about life
is to be a scientist

Human Evolution

                              data set 3

!!

   too random??

   tadpole to frog...
​​evolution before our eyes!

fossils include hard tissue like bones, teeth, shells and wood but can also reflect
 footprints and other marks.

D                                  data set 2

go forth and science!

breed = a collection of organisms within a species that have different characteristics as a result of selective breeding.

human dispersal
Out of Africa Model vs Multiregional model
Out of Africa model is now accepted =
single wave of Homo sapiens 100,00-65,000mya 
Homo sapiens speciated in Africa (Botswana) 200,000mya.
Homo sapien populations migrated through Eurasia outcompeting existing Homo species already present from previous migrations of Homo erectus and Homo Heidelbergus
mDNA analysis (highest in Africa) supports this model

 belief vs empirical evidence...

 # Amino Acids Differing from Human
Chimpanzee 0
Rhesus monkey 1
Rabbit 9
Pig 10
Dog 10
Horse 12
Penguin 11
Moth 24
Yeast 38

uh...no!

 Structures with similar anatomy, morphology, embryology and genetics but dissimilar functions are known as homologous structures.
​Structures that are superficially similar but anatomical dissimilar doing the same function are known as
analogous structures.​

  evolution is still misunderstood and not fully accepted...  

Homo sapiens closest ancestor = Homo erectus
(upright man) lived 1./9mya - 135,000mya
Homo habilus (nandy man) 2.4mya-1.4mya
Fossil evidence was first collected in 1856 in Neanderthal valley but dismissed as deformed Human.
1920 Saw the start of collections of intermediate species.
Africa was recognized as the seat of humanity in 1980s.
New discoveries as recently as 2015 in the Gauteng province of Africa of contemporaries of
Homo sapiens. 15 skeletons unearthed that were intentionally buried.
Tentatively identified as Homo naledi.
The journey continues...!   

when will "breeds", created via artificial  selection, need to be classified as separate species?

 1. difficulty understanding the concept of time...

  the measure of the genetic difference between sequences is a function of time since separation.
the predicted rate of molecular change can be used to predict time since divengence

what is meant by "fitness"?

D                               data set 4

type of speciation: Allopatric Speciation

                  1. bipedalism
                         evolved 6-7 mya
   chimps and gorillas are knuckle walkers
   Ardipithecus were fully bipedal 5.6 mya
                            permitted:                                        tool hunting/carrying/forelimbs use
                           infant care
accommodations to the shift in the center of gravity included:
a. skull modification to foramen magnum
b. femur/ increase length and weight            
c. knee/ankle joints increase strength
d. pelvis shorter and broader
   (which btw decreased birth canal size               leading to shortened gestation (smaller         heads) and longer alloparenting
​    (K-selection) of immature juveniles

  phylogenetic tree based on
# amino acid differences in hemoglobin 

2. ulnar oppostition = 
the opposable thumb
First seen in genus Homo including Neanderthals
allowed for a precision grip, manipulation,
tool manufacturing/use. 

Genus Homo exhibits 3 additional hand muscles to chimps... 

   transitional species

     evolution of the horse...
​    soooo many fossils  

​​​Charles Darwin

 misuse of the wordtheory

 mutations alter the sequence of a gene producing a variation which may be inherited.
Mutations are deletions, insertions, or substitutions of one or more nucleotides. 

                          data set 5

speciation

  phylogenetic tree based on
# nucleotide differences in the gene that codes for cytochrome C

   terrestrial or aquatic?

The point in our evolutionary past when the branch of human lineage diverged from the one that produced the great apes (orangutans, chimpanzees, bonobos, and gorillas) occurred in Africa 6.5  million years ago.

 perceived incompatibility with                 religious beliefs

  molecular phylogeny charts mutations  accumulating in the sequences of DNA, RNA or Proteins. 

Geographic isolation is not enough to cause speciation...
Reproductive isolation must occur.
Gene flow (migration) between populations permits interbreeding and sharing of genes...this decreases the chance
that speciation will occur. 

     and the evolution of the whale! 

       Evolution

A mule is the hybrid offspring of a female horse and male donkey. Because mules are sterile, they are not classified as a distinct species. 

  why?

​1. can't accept time as an abstract
2. feel science is not compatible with religious beliefs
3. don't understand the process of natural selection
4. say evolution is too random  
5. misuse the word theory

Evolution is still on trial...

The genetic variation on which natural selection acts may occur randomly, but natural selection itself is not random at all.

Are these two dogs really
​members of the
same species??

Equus asinus 

Are these two horses really
​members of the same species??

type of speciation: Sympatric Speciation

transcription factor Engrailed 1 (En1) promotes the sweat gland prodution 

Data sets that support evolution:

1. Artificial Selection
2.  Homologous Structures
3. Comparative Embryology
4. Molecular Evidence (molecular clock)
5. Fossil Evidence/Transitional Species 

  assembling phylogenetic trees:
​​classical vs molecular phylogenetics

 <--point of divergence

sexual dimorphism

Cytochrome C is a highly conserved enzyme involved in cellular respiration.
Science determines the relatedness of
species based on the variations they exhibit in their amino acid sequence.

Equus caballus  

convergent v divergent evolution

   fish that walk?

plus....
​5. decrease in olfaction/increase in vision
6. longer infancy/juvenile dependence
    (K-selection)
7. smaller gut
8. faster metabolism
9. loss of much body hair
10. increase in # sweat glands: 2-5million
      which produce +/- 12 liters sweat/day.
     (coincides with decrease in  hair                       distribution)
11. change in teeth alignment
12. emergence of a chin
13. emergence of a styloid process (muscle attachment for tongue and larynx)

1. non-random (selective) mating
2. gene f low (migration)
3. natural selection
4. genetic drift (inbreeding)
5. mutations

phylogenetic tree based
on morphology 

   birds that swim?

only a small percentage of organisms that
have ever lived become fossils. Fossilization is most likely to occur in catastrophic conditions. Remains take on average 10,000 years to fossilize.

if one or more of  these influences occur in a population,
​evolution is occurring in that population.

natural selection

                         What are some of the many fatal flaws of eugenics.
 1.  Complex traits like intelligence are not determined by single genes and simple Mendelian 
      inheritance.
 2. Complex traits exhibit a strong environmental component (nature/nurture).
 3. Homozygosity, the end game for eugenics, is genetically disadvantageous for a species.
 4. Inbreeding, a byproduct of selective breeding, increases the likelihood that inherited defects 
     appear in subsequent generations.
 5. Those most suited for survival out produce those poorly suited, therefore, the genetically fit 
     survive naturally.

and we are huMAN emphasis on MAN...?

what is eugenics?

interestingly...
non-African humans have 1.5-2.6% Neanderthal DNA
Some Melansians have 4-6% Denisovan DNA 
A 40,000 ya skeleton in Romania showed 11% Neanderthal DNA = 5 generation past interbreeding 

Hair is unique to mammals.
It provides insulation and protection.
It permits social displays to indicate aggression or agitation.
The transition to bipedalism would have coincided with a change in lifestyle due to environmental changes (dry/hot) and diet.
So the transition to naked skin and an increase in sweat glands occurred 1.6 million years ago to offset greater heat loads.

 one species doesn't "turn into" another species.
​ There is a gradual alteration of a subpopulation due to mutations and natural selection
​ = speciation

        what is a fossil?

3. encephalization:
​increased brain capacity
early Homo species has same cranial size as chimps.

Homo erectus had a larger brain
Homo neanderthalus had largest brain capacity.
temporal lobes, pre-frontal cortex and cerebellum increase in size strengthening decision making,
social/behavioral skills, language.
 and cognition.

coincides with tool use 2.5 mya

a transitional form species is an intermediate between two different species. 

species = a group of organisms capable of interbreeding and producing fertile offspring

How does a new species form?
Reproductive isolation!
A single population is divided into two groups.
Mutations occur in members of these different groups.
Since mutations are random events,
the DNA of the members of the two groups will accumulate different mutations.
These different mutations may lead to differences in phenotype. 
The environment of the two different populations 
​selects the favorable phenotype of that populations for that environment.
In this way, each new population develops greater and
​greater differences from one another.
Should the two populations meet again, if they can no longer produce fertile offspring, 
the two populations are considered two species. 

Microevolution =
changes in the allele frequencies in a population over time. 

   4. sexual dimorphism:
a. ​decrease in size of male canines and male brow ridges
b. subQ body fat distribution
c. hair quantity/distribution
d. "hidden estrus"
      12 month fertility with no                  external signs
5. 15% size difference

there is a "tendancy" for anthropology to focus on  the descent of our species using models which focus on male evolution

what could Darwin not know about when he described natural selection...??? 
mutations! 

yes...!

allele/genotype frequencies
WILL REMAIN CONSTANT
​(in equilibrium)
 unless one or more the the following occurs:

Hominins include modern humans, extinct human species and all our immediate ancestors including members of the genera Homo, Australopithecus, 
​Paranthropus and Ardipithecus.

  broiler chickens in the     1950s averaged
 <1 kg or about 2lbs.
 by 2000, the breed had been artificially selected for muscle (meat) to the tune of an average
>4kg or about 9 lbs.

radiometric dating of fossils

same species!!

      data set 1

   phylogenetic trees are branching diagrams that show the evolutionary history of a group of organisms

 are Home sapiens still evolving...? YES! 

evolutionary adaptations 

  Taxonomists use the protein cytochrome C 
​for DNA bar-coding and species identification because its amino acid sequence tends to be highly conserved among related species, with little variation between members of the same species. 

 an organism is covered in mud or ash.
this sediment protects the carcass from scavengers, erosion and decay.
 the tissues of that organism are slowly  replaced with the minerals from the soil in which is was buried.

To simply believe in something is to accept it is true without supporting empirical evidence.