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Introduction

In this section you will be introduced to some scientific theories about life’s history. One of the popular theories of life’s history isthe theory of Evolution. Another is the theory of Intelligent Design. In order to be able to evaluate information critically, it is important to firstunderstand how people form knowledge, and to be able to differentiate between data and conclusions.

How do we know?

How do we know what happened in life’s history? We cannot do experiments on the origin of life. There are also no historical records about the origin oflife. We have to rely on data we find. From this we draw conclusions about what might have happened in life’s history.

http://www.youtube.com/watch?v=pXs-693ERSc

How do we know?

This is a clip movie about how people get knowledge in general, and how people can get knowledge about origins, in particular.

Data and conclusions

Data means information people collect using their senses : sight, touch, hearing, feeling, smell. Usually when a scientist collects data, other scientists will agree with him/her about this data. Sometimes other scientists might question whether the data was correctly recorded, or whether the data is a forgery, but usuallyscientists trust that the data was collected correctly.

Conclusions are patterns people think up to help to make sense of data. When a scientist draws a conclusion from some data, he/she makes various assumptions. Assumptions are thoughts which peopletake to be true, without proof. Assumptions should be justified so that people can evaluate their validity (how likely they are to be true). It is common for scientists to disagree on the validity of assumptions and conclusions, even when they do agree on the data from which the conclusions are made. This is because different conclusionscan often be drawn from the same data.

http://www.youtube.com/watch?v=AVCPfrp-VDo

Data conclusion

Life’s history

APBiology: Molecular Evolution and the early earth: (External Link)

The extremely long period of time over which life has developed on earth can be represented in various ways. Examine the diagrams below:

Taken from (External Link)

The various time periods are related to dramatic climate changes that the earth has experienced over time. This is partly due to what is called continental drift :

Continental drift:

This theory proposed that all land was at one stage joined to form the supercontinent Pangaea , which split into Laurasia in the north and Gondwana (or Gondwanaland) in the south. See (External Link)

There is much evidence that continental drift occurred and is still continuing today:

There is biogeographic evidence of related species in widely isolated areas, such as the very similar flightless birds like the rhea in South America, the ostrich in Africa, the moa in NewZealand, the emu and cassowary in Australia. They are thought to have developedfrom a common ancestor on Pangaea. As the climate gradually changed, organisms slowly adapted and underwent speciation in response to changes in thetemperature and vegetation around them.

OTHER EVIDENCE for continental drift include the following, showing that the climate in some areas is now very different from what it once was:

  • The discovery of fossilized tropical plants under Greenland’s ice caps
  • Glacial landscapes in central Africa and Central America
  • Whale fossils in the Sahara desert
  • The discovery of subtropical plant fossils in Antarctica, indicating that it once had a much warmer climate and lush vegetation.
  • South African examples of continental drift include the discovery of the fossils of marine organisms in places that are VERY far from the sea, such as bivalves and ammonites in the Makhatini flats in northern KZN, and marine trilobite fossils in the Karoo.
Ammonite fossil
Trilobite fossil

Plate tectonics

This theory provides a mechanism for continental drift. The continents we know today rest on large, interlocking plates of land called tectonic plates, whichfloat on a hot, molten layer that shifts them. Slow movements of these plates move continents further apart, but more rapid movements of the plates areevident when earthquakes occur. The continents are still moving apart at the rate of just a few cm per year.

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
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Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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