Understanding Evolution

“Life goes on!”

© Harshal Ganpatrao Hayatnagarkar version 2013.12.23

CC BY-SA 3.0

Why do we feel hungry?

What keeps our body temperature around 98.6 ℉ or 37 ℃ ?

Why our wounds are healed, by themselves?

How does our body fight diseases?

Why certain variety of wheat is more productive?

Why certain computer software perform better than others, in impossible situations?

Are we alone in the Universe? Can there be Life elsewhere?

…

Few questions…

Although not apparently so, these questions are connected and so are their answers.

The thread connecting them is –

Theory of Evolution

The Journey

What is Evolution?

How to study evolution?

History of Life as Evolution

What next?Summary

What is Evolution?

Credit: M. F. Bonnan

“History of changes”

Passive process.

NOT limited to biology.

NOT synonymous to progress.

NOT same as Origin of Life.

Essentially interplay of variations over time.

Explained by various theories (to be discussed later).

Okay, so Evolution is…

Origin of Life

time

Evolution of Life

This presentation is about Evolution of Life,

which starts AFTER

Origin of Life.

Why study evolution?

Because it is the study of history of Life,

the only known phenomenon in the Universe.

Medicines Food Climate Education

Technology Economics and finance

Sociology Exobiology

Why study evolution? + bonus

“Nothing in biology makes sense except in the light of evolution”

– Theodosius Dobzhansky

(Evolution) is a general postulate to which all theories, all hypotheses, all systems must hence forward bow and which they must satisfy in order to be thinkable and true. Evolution is a light which illuminates all facts, a trajectory which all lines of thought must follow — this is what evolution is.

Why study evolution?

How to study evolution?

This is a long story, so behold !

Three aspects

Evolution

Diversity

Time

Implications

+ one needs tools and techniques to study each of these aspects.

1. Diversity Aspect

Evolution

Diversity

Time

Implications

To understand

so much diversity,

that once existed,

exists today, including the Humans

and

probably would emerge,

and to which

we are the witness.

Quest

Grouping

Literally means ‘Classification’ in Latin.◦ Grouping organisms in different classes (lets

call them ‘buckets’ for simplicity).◦ Well, putting buckets into bigger buckets.◦ Deriving common properties for each bucket.

Linnaean Taxonomy◦ Originally defined by Carolos Linnaeus in 1735.◦ Based on morphology.◦ Grouped organisms into groups and subgroups.◦ Organisms were created by God and Carolos

only classified and named them.

Taxonomy

Linnaean Nomenclature◦ Binomial nomenclature

Naming organisms by dichotomous key Meaning ‘two words’.

◦ [Genus species].◦ For example

Humans Homo sapiens Elephant Elephas maximu Potato Solanum tuberosum

Groups (we called them buckets earlier)◦ Common features abstracted.◦ Resulted in initial hierarchy.

Final hierarchical definition◦ With criteria◦ E.g. Kingdoms

Plantae, Animalia, Fungi.

Taxonomy of Species

Familiar Route *

abstract class Phylum extends Kingdomabstract class Family extends Order abstract class Genus extends Family…abstract class Homo extends Genusclass Homo_Sapiens extends Homo

harshal = new Homo_Sapiens(“Harshal”);

Only ‘Species’ can be instantiated

*Java programming language

It’s different ! Taxonomy has raised more questions than it

answered.

Organisms are similar to one another…◦ How much similar?◦ Why those similarities?◦ For example, fox is similar to wolf.

As well as different…◦ How much different?◦ Why those differences?◦ Fox is not wolf.

In wrong buckets - Whales were fishes once.◦ Classification based on appearances.◦ And whale is NOT a fish, only if one looks INSIDE.

To err is Human

In addition, there are hints from the development of embryos of various species.

Tail at origin tells tale of origin.

Developmental Taxonomy

Correction of such mistakes did not leave taxonomy untouched of evolution, too.

Taxonomy has itself been evolving since then.

Evolution of Taxonomy

Morphology Anatomy Physiology Microbiology

BiochemistryGenomicsProteomics300

years of journey

Linnaeus1735

Haeckel1866

Chatton1937

Copeland1956

Whittaker1969

Woese et al.1977

Woese et al.1990

2 kingdoms 3 kingdoms 2

empires4

kingdoms 5 kingdoms 6 kingdoms 3 domains

(not treated)) Protista

Prokaryota Monera Monera

Eubacteria Bacteria

Archaebacteria Archaea

Eukaryota

ProtistaProtista Protista

EukaryaVegetabilia Plantae

Fungi Fungi

Plantae Plantae Plantae

Animalia Animalia Animalia Animalia Animalia

Evolution of TaxonomyWikipedia:Taxonomy

2. Time Aspect

Evolution

Diversity

Time

Implications

If two objects are separating at rate of 1 inch per yearThen

After 1 million year, they would be 25.4 kilometers apart.

12 % of

Geologicaltime

All major phyla.

First fishes.

4500 million years history of the Earth

Cosmic Calendar To give glimpse of events occurred in the

history of the Universe to fit into the scale a common person can understand◦ From Big Bang till today◦ Thirteen billion years of the Universe’s history

scaled into 365 days of a year

January 1st, 00:00:00 AM Big Bang

Each month is roughly equivalent to a billion years

Prof. Carl Sagan

Court

esy

- A

rif

Babul

But from such a remote past, what could survive to tell us the story?

Literally means ‘Obtained by digging’ in Latin and studied under ‘Paleontology’.

A Fossil can be past impressions about the living being (like a thumb impression). ◦ Impression of a leaf on a then-wet mud.◦ An insect caught in a tree amber.◦ Petrified skeletons of animals.

All one gets from such an antiquity is a fossil. A paleontologist must make sense out of them, such as to ‘extract’, preserve, connect and date the specimen.

Fossils can still tell the story of the organism when it was dying.◦ Morphology◦ Anatomy◦ Physiology (possibly)

Fossils - The Story Teller

Challenges◦ Identifying if a specimen is a fossil.◦ Recovering a fossil as complete as

possible.◦ Identifying parts and whole of a

fossil.◦ Identifying organism of that fossil.◦ Determining age of a fossil.◦ Preserving for future study.

Fossils - The Story Teller

Informally, an organism still alive representing a lone species whose other relatives are extinct.◦ Coined by Charles Darwin himself.◦ To understand certain anomalous species that have

survived evolutionary pressure for very long time.

For example, platypus or duck-bill.

Living fossil

To explain diversity…

Lamarck’s Theory

Darwin-Wallace’s Theory

Mendel's Theory

Neo-Darwinism

Modern Evolutionary

Synthesis

Theories have been evolving since last 200 years to answer these questions

‘Inheritance of acquired characteristics’◦ For example, giraffes

stretched neck and passed it to progeny generations after generations.

It does not hold good today.◦ There is no known reverse

path from phenotype to genotype.

Lamarckism

Jean-Baptiste Lamarck

Explains origin of diversity over time i.e. Evolution

Charles Darwin and Alfred Russell Wallace◦ Independently and then together◦ Popular as ‘Darwinism’ or ‘Survival of Fittest’

Darwin influenced by Malthusian Catastrophe◦ Human population tends to increase a lot faster than food

supply, which may lead to catastrophic implications for entire planet.

Theory of Natural Selection

Charles Darwin Alfred Russell Wallace

Origin of species

Multiplication

Competition

Variation

Competition

Adaptation

SurvivalGrowth

Multiplication

Theory of Natural

Selection

Speciation

To understand Theory of Natural Selection,

we should understand role of diversity and ecological niche.

Kind of approximation of term ‘habitat’.

Subset of Ecosystem. Hyperspace of multiple dimensions. Dimensions can be temperature,

Humidity, salinity, language and so on. For example

◦ Salt water/fresh water.◦ Arctic deep ocean water.◦ Amazon rain forests.◦ Highland forests.◦ Top and bottom of Maple trees.◦ Roof-tops in Manchester city.◦ Marathi-speaking regions in India.◦ Traffic signals in India .◦ and almost anyplace where life-forms

exist.

Ecological Niche

Source: http://www.geol.umd.edu/~jmerck/GEOL388/lectures/06.html

Source: http://hhh.gavilan.edu/rmorales/EcologySpring2008.htm

On Galapagos Islands Darwin observed variety of finches, adapted for respective habitats.◦ High altitude vegetation◦ Highland forests◦ Lowland forests◦ Bushes◦ Shoreline vegetation

Even various levels of the same habitat, for example, from top to bottom of tree trunk.

Ecological Niche

Source - http://hhh.gavilan.edu/rmorales/EcologySpring2008.htm

Source - http://14yunhyu.wordpress.com/2013/08/31/d-2d-macroevolution/

Source: http://www.geol.umd.edu/~jmerck/GEOL388/lectures/06.html

Species adapt to suit to their habitat. Alternatively, only suitable species survive in a habitat.◦ Adaptation for food, safety, nursing and

so on.

Competitive Exclusion Principle OR Gause’s Law◦ No two species can occupy the same

niche in the same environment for a long time.

◦ “Complete competitors cannot coexist”.◦ Thus if two organisms occupy exactly

same niche, then they are the same species.

Ecological Niche

Source - http://hhh.gavilan.edu/rmorales/EcologySpring2008.htm

Source - http://14yunhyu.wordpress.com/2013/08/31/d-2d-macroevolution/

Life forms are food for others.◦ Visually chains and

webs/networks.◦ Mostly undiscovered.◦ Delicate balance in ecologies.

Human interference.◦ Try removing few species

here and there, the ecological collapse may happen (See Gaia Hypothesis).

◦ For example, cell towers and insecticides are killing bees, reducing crop output.

Food Chains and Webs

Source: http://en.wikipedia.org/wiki/File:Chesapeake_Waterbird_Food_Web.jpg

Population/individual becomes better suited to its habitat.

Caused by variation through◦ Mutation (random variation in genes)◦ Breeding (sexual reproduction)◦ Horizontal gene transfer (Asexual borrowing. Typically

occurs in bacteria).

For example, in highland forests, those finches will survive better which can crack nuts with hard shells.

Adaptation

Adaptive Radiation Evolution of ecological and phenotypic

diversity within a rapidly multiplying lineage.◦ Starting with a recent ancestor, this process results

in an array of species with different traits with which they can exploit a range of divergent environments.

◦ For example, over generations few finches moved up the tree and few moved down.

Likely to trigger Evolutionary Radiation in local ecosystem.

Source - http://14yunhyu.wordpress.com/2013/08/31/d-2d-macroevolution/

Source - http://hhh.gavilan.edu/rmorales/EcologySpring2008.htm

Speciation Emergence of new species.

◦ Species : A group of organisms capable of interbreeding and producing fertile offspring.

Consistent variation passed to offspring.

An increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace.◦ Essentially adaptive radiation spread across species.◦ Essentially many branches in a phylogenic tree.

Evolutionary Explosion◦ A rapid radiation in a relatively short span of time.◦ For example, Cambrian Explosion, The Internet.

Cambrian Explosion◦ Span of 10 million years happened 425 million years before.◦ Blueprints of all known phyla emerged in this short span.

Evolutionary Radiation

Darwin postulated that species change gradually and continuously.

However, Stephen Jay Gould and others observed stasis and sudden speciation, called as ‘Punctuated Equilibria’.

Species ‘accumulate’ changes and then ‘suddenly’ radiate into new species.

Introduced and reinforced idea that species are Darwinian individuals and not just classes.

Reasons are unknown.

Punctuated Equilibria

Source - http://en.wikipedia.org/wiki/File:Punctuated-equilibrium.svg

All these variations do not survive over time.

In fact, 99.9% of species

that have ever existed, are now extinct,

including dinosaurs.

Modes of Natural SelectionPredation Mating

Climate changeExternalities (such asteroid

impact)

Artificial Selection (Natural selection in human context)

Job interviews

Marriages

Markets

Genetically Modified Food/Organisms

&Selective breeding

Conflicts and Wars

Individuals survive due to useful variations survive and perish through harmful ones.

Units of selection◦ Self-reproducing molecules◦ Genes◦ Cells◦ Individuals◦ Groups◦ Species◦ Societies◦ Nations

Selection

Ecological contrasts◦ Snow◦ Black soot deposited on roof tops.

Altered predator-prey pattern◦ Black soot was getting accumulated on roof-tops, in all seasons.◦ White moths were becoming visible even during winter, on

accumulated black soot on roof-tops and predators could find and eat them.

◦ Thus increasing black moths population over white ones.

Darwin’s Peppered Moths

Black moth Black mothWhite moth White moth

Black soot deposited by textile factories

Snow deposited in winter

Black soot from textile factories of Manchester

“Slow though the process of selection may be, if feeble man can

do much by his powers of artificial selection, I can see no limit

to the amount of change, to the beauty and infinite

complexity of the co-adaptations between all organic beings,

one with another and with their physical conditions of life,

which may be effected in the long course of time by nature's

power of selection.” Charles Darwin

Probably origin of term ‘Natural Selection’.

Life cycle of a sexually reproducing organism

Source: http://en.wikipedia.org/wiki/File:Life_cycle_of_a_sexually_reproducing_organism.svg

Fitness is NOT about being strong or healthy.

“Ability to survive and to reproduce, both”◦ Collective quality of a population of species.◦ Also thought in terms of average contribution to ‘Gene

pool’.◦ Simply, determines if a species would continue to

survive.

Fitness

But what makes a baby elephant as strong as its parents?

OR

How traits are transferred from parents to children, in general?

Mendel’s Laws◦ Law of Segregation ◦ Law of Independent Assortment.

Discovery-rejection-rediscovery◦ Work published in 1865-66.◦ Initially rejected by scientific community of his time. ◦ Later rediscovered in 1900 independently by Hugo de Vries and Carl

Correns and was acknowledged.

A set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their offspring;◦ Units of heredity called as Factors

Today known as Genes Basis of chromosomal inheritance and genetics.

Mendelism

Gregor Mendel

Law of Segregation ◦ When any individual produces gametes, the

copies of a gene separate so that each gamete receives only one copy.

Law of Independent Assortment◦ Alleles of different genes assort independently of

one another during gamete formation.◦ Also known as "Inheritance Law"◦ True only for ‘unrelated genes’

Mendel’s Laws

Mendel’s Laws

Discovery of nucleic acids DNA and RNA.◦ Structure and role of

nucleic acids in inheritance.

◦ Analogous to Mendel’s work.

Genes - Segments of DNA and RNA.◦ Functional units of

inheritance.◦ For example, color of

eye/hairs.

GeneticsJames

WatsonFrancis Creek

What Mendel called ‘factors’ then, are called as Allele today.

Allele◦ Either of a pair (or series) of alternative forms of a gene

that can occupy the same locus on a particular chromosome and that control the same character;

◦ “Some alleles are dominant over others”

Units of inheritance

Darwinism + Chromosomal inheritance

‘Gene-centered view’ or ‘Selfish gene theory’◦ Holds that evolution occurs

through the differential survival of competing genes as if such genes are selfish.

◦ Even further, altruistic behavior of organisms are in fact manifestations of selfish genes.

◦ Introduces concept of ‘replicator’ and two instances of them – Genes and memes.

◦ What genes are for organisms, memes are for cultures.

Neo-darwinism

Generative encodingPhenotype

• Observable trait• For example morphology, anatomy,

behavior and so on.• Expression of genes• Extended Phenotype• For example bird’s nest.• Extended expression of genes.

Genotype

• Genetic make-up• For example, chromosomes, nucleotide

sequences in some cell organelles.• Translates into phenotypes.• Replication through extra-dimension of

time.

Genetic drift

Spectrum of biological complexity

Amino acids Proteins Nucleic acids (RNA & DNA)

Chromosomes and organelles

CellsTissuesOrgansIndividuals

Groups, herds, societies and

nationsEcosystem Planet

Brings together fields that are separated◦ From geology to paleontology.◦ From molecular biology to ecology.◦ From linguistics to political science.

Neo-Darwinism becomes subset.

It becomes possible to explain many phenomena due to borrowed learning.

Modern Evolutionary Synthesis

http://en.wikipedia.org/wiki/File:Structure_of_Evolutionary_Biology.png

Evolution = Study of variation over time and space

◦ Space Variation across individuals at any given time.

◦ Time Variation across individuals in past and present.

Systematics◦ Study of the diversification of

life on the planet Earth, both past and present, and the relationships among living things through time.

How to study evolution?

Evolution – A primer

Phylogeny, The Family Tree “The history of organismal evolution” 1

◦ Evolution is regarded as a branching process, [whereby populations are altered over time and may speciate into separate branches, hybridize

together, or terminate by extinction]. This may be visualized as a multidimensional character-space that a population moves through over time.

Basically family tree of species

Further reading

Tree of Life from Phylogeny point of view

1. Single entry for all the animals

No surprise that microbes account for more than half biomass on Earth.

2. Common ancestor of animals and fungi

Tree of Life (by David Hillis, based on genome sequences)

Explore more at http://onezoom.org

Human Evolution Linux Evolution

Variation - An individual is different from others◦ Of same kind – Attributes shared,

values differ.◦ Of different kind – Attributes differ,

values differ.

Classification◦ One combines similar individuals

into a group, and then such groups into larger groups and so on, forming a hierarchy of groups called Taxonomy.

◦ Shared attributes of groups in a taxonomy

◦ In biology, species are loose groups of similar, compatible individuals, different from one another.

Understanding variations

Sources of variation

Error in copying information

Recombination

+

+ +

+

CreativityBorrowing/snatching information

Mutation Horizontal transfer Sexual reproduction Creativity

time

Evolution = Variation over time

Macroevolution• Meteorology• Economics• Sociology• Game theory• Ecology• Population genetics• Behavioral science

Microevolution• Anatomy• Physiology• Genetics• Microbiology• Chemistry• Quantum mechanics

Individual

4. Growth and multiplication•Mating

1. Variation•Useful•Harmful

2. Competition•In presence of limited resources

3. Selection•Survival

1. Adaptation

2. Radiation

3.

Speciatio

n

Microevolution

Proteins

RNA

DNA

Structure and behavior

Physiology

Cellular

Metabolism

Microevolution

Micro-macroevolution

Ecosystem

Species

Individual

Study of changes that occur at or above the level of species, in contrast with microevolution.

For example, a new species emerges or a group of species goes extinct.

Explosions and extinctions - Two recurring patterns in macroevolution .

Macroevolution

Source: http://evolution.berkeley.edu/evolibrary/article/evoscales_01

Extinction = Death of a species ◦ Extinction of species is continuous process.◦ Sometimes, widespread and more destructive.◦ Either due to evolutionary pressure or external events.◦ Great evolutionary significance.

Extinctions A B C D

EDiversity

Time (million years ago)

Major causesAsteroid impact Volcano Fall in sea levels

(A) Ordovician-Silurian

• 450-440 Mya (million years ago)

•60-70% of all species - 2nd largest of all.

(B) Devonian-Carboniferous

• 375-360 Mya•70% of all species.•Extinction pulses within this period.

(C) Permian-Triassic

• 250 Mya•Deadliest of all, Known as ‘Great Dying’.

•Killed upto 95% of all species.

•End of Trilobites, arguably longest surviving organisms.

(D) Triassic-Jurassic

• 200 Mya•Killed 70-75% of all species.

(E) Cretecious-Paleogene

• 65 Mya•Killed 75% species.•Known for end of dinosaurs.

Big Five Extinction Events

A B C D

EDiversity

Time (million years ago)

It’s not all that bad…as in creative destruction, creation follows destruction.

Sometimes, more creatively…

Rise in speciation in relatively smaller time window. Accelerated increase in diversity in geologically shorter

time. Usually, driven by rush to fill empty niches. Could be triggered by an innovative trait and sustained

by competition. For example development of – ◦ Photosynthesis.◦ Oxygen-based metabolism.◦ Aging.◦ Sex.◦ Eye.◦ Endoskeleton and jaw.◦ Endothermic mechanism.

Explosions

Approximately 540 million ago. All major animal phyla emerged from this period. Blueprints for all vertebrates including fishes, dinosaurs and humans.

Triggered by –◦ Innovation of ‘eye’.◦ Increase in oxygen levels.◦ Snowball earth.◦ Sustained by arms race thereafter.

Rise of trilobites ◦ Arguably longest lived organisms till date – 300 million years.◦ Highest inter-species diversity.

Cambrian Explosion

Cambrian explosion

• 540 Mya.• All major animal

phyla emerged from this period• Blueprints for

vertebrates including humans.

• Triggered by –• Innovation of ‘eye’.• Increase in oxygen

levels.• Snowball earth.• Sustained by arms

race thereafter.

Devonian explosion

• 440 Mya.• First major adaptive

radiation of land-based life such as rise and spread of free-spore vascular plants.

• Rise of fishes, and known as ‘age of fishes’.

Triassic explosion

• 240 Mya.• After the largest

extinction event ‘P-T’.

• Rise of dinosaurs.• Rise of first true

mammals.

Paleogene explosion

• 60 Mya.• Adaptive radiation of

mammals, birds and reptiles.

Notable explosions

When different organisms develop similar features to survive in a common niche.

For example, streamlined body for swimming swiftly in the water.

Convergent Evolution

Shark (Fish)

Whale (Mammal)

Penguin (Bird)

Dolphin (Mammal)

Kronosaurus (Reptile/dinosaur)

Convergent Evolution

Okay, Evolution is a great story.

But, what if the tape is played again?

For example (popular in sci-fi movies)◦ Imagine you go on a jungle safari, albeit of

Jurassic age (150 Million years before present).◦ You make a simply change, say killing a butterfly

and come back to present time.◦ Should there be any impact of that killing on

future?◦ Alternative History.

What if the tape played again?

Small perturbation (at one place) may lead to large effects (at other places).

Observed by Edward Lorenz while modeling weather patterns that very small changes in values (such as a flap of butterfly’s wings) lead to dramatic changes in patterns (such as hurricane formation) over time. Hence the name.

For example , using wind speed of10.0000001 Km/h instead of 10 Km/h may lead to vastly different predictions.

Chaos Effect (Butterfly Effect)

Edward Lorenz

time

Chaos is NOT same as randomness. Randomness necessitates denial of any pattern or order. Whereas chaos is often termed as Hidden Order.

“Extreme sensitivity to initial conditions”.◦ Vastly different outcomes over time due to slightly different initial

conditions.◦ Chaotic is property of all non-linear dynamical systems.◦ Highlights significant path dependence.◦ For example – Weather, Stock market crashes, Epidemics, etc.

Always prevalent situation – any point in space-time is an initial condition.◦ Analogous to sliding rule, the window of study moves thus making any

point on rule as start of the window.◦ Interesting part is about emergence of the other end of this window.

Chaos Theory

Emergence = property or behavior of a system demonstrated by none of its individual parts but collectively by them.◦ For example, intelligence is emergent property of

brain, made from zillions of neurons, though none of them individually has this property.

◦ For example, locomotion is property of automobile, but none of its parts.

Natural selection makes it possible to achieve similar goals with different routes.◦ For example, due to convergent evolution, vision,

flight and streamlined body have been emerged in different species in the past.

Actually it may not matter in many cases whether we play the tape once or many times, due to phenomenon namely Self-organization.

Chaos and Emergence

Changes in Environment

Changes in Population

Changes in

Individual

Self-organization Examples

A special kind of emergent phenomenon – Spontaneous order arises out of local interactions of components.◦ For example, crystallization, galaxy formation, flocks of birds,

multicellular organisms, human societies and so on.◦ Islands of predictability in the ocean of unpredictability.

Perhaps, it’s an answer to every question regarding Life, or at least participatory.◦ Life is because-of, is a and has Self-organization.◦ Natural selection itself is a kind of Self-organization phenomenon.

Self-organization

Self-organization

Chaos

Helps achieve similar results from different initial conditions. Thus acts as opposite of chaos.

EvolutionVariations

Combinations

Populations

Competitions

Generations

Overview of Factors

3. Implications Aspect

Evolution

Diversity

Time

Implications

Highlights some important patterns in

evolution

Functional integration

Functional differentiation

Complexity trend

Information aspect of evolution

The Major Transitions in Evolution

From To Notes

Replicating molecules"Populations" of molecules in

compartmentsCan't observe

Independent replicators (probably RNA)

Chromosomes RNA world hypothesis

RNA as both genes and enzymes

DNA as genes; proteins as enzymes

Prokaryotes Eukaryotes Can observe

Asexual clones Sexual populations Evolution of sex

ProtistsMulticellular organisms — animals,

plants, fungiEvolution of multicellularity

Solitary individuals Colonies with non-reproductive castes

Primate societiesHuman societies with language,

enabling memesSociocultural evolution

The Major Transitions in Evolution

Observations Increasing biocomplexity through Integration Smaller entities often have come about together to form

larger entities. ◦ For example Chromosomes, eukaryotes, sex multicellular colonies.

Observations Often smaller entities

◦ Have become differentiated as part of a larger entity. For example DNA & protein, organelles, anisogamy, tissues, castes

◦ Are unable to replicate in the absence of the larger entity. ◦ e.g. Organelles, tissues, castes

◦ Can sometimes disrupt the development of the larger entity.◦ e.g. Meiotic drive (selfish non-Mendelian genes),

parthenogenesis, cancers, coup d’état

New ways of transmitting information have arisen.◦ e.g. DNA-protein, cell heredity, epigenesis, universal grammar.

Complexity has been rising since origin of life.

Cambrian Explosion ◦ A tipping point.◦ Accelerated pace of

increase in complexity.

◦ A pattern in evolution, typically preceded by an extinction event/span.

Biocomplexity

Predator-prey model Quasi-closed system/habitat,

populations of species affect each other.

In predator-prey model, changes in demand and supply.

Complex relationship in presence of multiple predator and prey species.

Such patterns affect environment.◦ For example, if a grass consumed by

rabbits will affect population of not only rabbits, but also wolfs.

A more complex example

Bacteria HerbRabbit

Wolf

Single mutation in a bacterium can significantly affect an herb, which forms significant diet of a species like rabbit and thus affecting population of wolves too, that feed upon rabbits.

Life forms are food for others.◦ Visually chains and

webs/networks.◦ Mostly undiscovered.◦ Delicate balance in ecologies.

Human interference.◦ Try removing few species

here and there, the ecological collapse may happen (See Gaia Hypothesis).

◦ For example, cell towers and insecticides are killing bees, reducing crop output.

Food Chains and Webs

Source: http://en.wikipedia.org/wiki/File:Chesapeake_Waterbird_Food_Web.jpg

Biosphere is a self-regulating entity.

“Abiota affects biota and vice versa”.

Cycles in a Daisy World.

Model for climate change.

Gaia HypothesisProf. James

Lovelock

Now a fact instead of fiction.

Major contribution by humans.◦ By Gaia hypothesis, climate change in turn will affect humans.◦ Rise in ocean levels, resulting into submerging of coastal cities.◦ Frequent hurricanes and cyclones.

Changes in seasons to affect harvest.◦ ‘Malthusian catastrophe’

However, humans will affect humans too.◦ ‘Behavioral sink’

Global Warming

“A condition or event by which a population returns to subsistence level conditions once population growth outpaces agricultural growth” – Wikipedia◦ An Essay on the Principle of Population published in 1798.◦ Inspired Charles Darwin, to late discover Theory of Origin

of Species.

Criticism◦ New knowledge and technology can avert such crisis. For

example, Green Revolution.◦ Socio-economic aspects such as birth control and

urbanization play their role too.

Malthusian CatastropheThomas Malthus

Increasing population has its impact on itself too.

An experiment to understand impact of overpopulation.◦ From 1947 to 1972.

◦ Published initial result in Scientific American in 1968.

◦ Though experiment involved rats, results are indicative to humans too.

Behavioral sink

John B. Calhoun

Many rats placed in a relatively small area.◦ Area divided into four rooms, with decreasing

amenities such as food, water and protection.◦ Rats in each room showed different behavior.

Least resourceful room was termed as Behavioral Sink.◦ Rats showed destructive behavior, especially

towards weaker rats such as females and babies.

◦ It resulted into inability of females to carry through pregnancy and mortality rates as high as 96 percent.

Similar indicative behavior can be seen in patches of human societies too.

Behavioral sink – The Experiment

Economy crisis◦ Faltering growth.◦ Booming and busting bubbles.◦ Unemployment.◦ Inequality.

Energy crisis◦ Depleting fossil fuel sources.◦ No viable alternative in sight.

Ecology crisis◦ Mining, petroleum and heavy industries.◦ Automobiles and livestock.◦ Shrinking fisheries, forests, glaciers and

icecaps.

Humanity Crisis

Ecology crisis

Economy crisis

Energy crisis

Humanity Crisis Ahead

What next?

Evolution has brought us here.

It will guide us from here.

Change is the only constant thing.◦ Hence evolution is omnipresent and almighty.

Evolution is interplay of scale and diversity over time.

Never underestimate power of small change.◦ Butterfly effect◦ An action sets the Universe on a new course, every

time and all the time.

Summary

(“Everything else is an illusion” – Bhagvadgeeta)

Prof. N Swaminathan and other colleagues.

Acknowledgement

AND

Thank you !To be continued with Evolution: Understanding facts

Being evolutionary is not a bad idea, perhaps because

being survived as fittest is not a bad idea too.