Editing 1338: Land Mammals

{{comic
| number    = 1338
| date      = March 5, 2014
| title     = Land Mammals
| image     = land_mammals.png
| titletext = Bacteria still outweigh us thousands to one--and that's not even counting the several pounds of them in your body.
}}

==Explanation==
{{incomplete|The division of animal blocks are clear but only 6 are labeled. Some qualified guesses as to how the other (at least the largest) blocks are divided should be possible... What about the layout of the blocks?}}

This comic shows the total weight of mankind and other land mammals. 
Only in the last century or so have humans, and their pets and livestock, come to occupy such a great proportion of the earth's land mammal mass.

Per the diagram, there are 358 million tons of humans, 864 million tons of pets and livestock, of which 520 million tons comes from cattle, and 34 million tons of wild animals; for a total of 1.3 billion tons.

As of March 2014 the world population was about 7.2 billion people so the comic assumes an average human weighs of about 49.7 kg: 7.2 billion people &times; 49.7 kg = 358 billion kg = 358 million tons. Since it's very unlikely that Randall assumed 49.7 kg per person, it is more possible that he assumed the average human weighs 50 kg and the world population is 7.16 billion people. As more than 25% of the [http://www.worldometers.info/world-population/world-population-gender-age.php worlds population is below 15 years of age], and many people live in poverty (i.e. no chance of obesity), this estimate may be very valid, although it may at first appear on the low side.

Cattle is by far more heavy than the total human population, but we do manage to outweigh both Sheep and Pigs - which may come as a surprise - as these animals probably by far outweigh the population in the countries that produce the main part of the worlds meat from such animals.

It is interesting to note that the world's heaviest land dwelling animal - the elephant - only takes up one square! It is the only type of wild animal to be singled out in the comic.

There are 8 distinct blocks of wild animal (elephants and 7 others). There are 13 distinct blocks of pets and live stock (only the top 5 are labeled - in order of weight they are: Cattle, Sheep, Pigs, Goats and Horses). Dogs would properly also take up a large part - it could be the 6th largest, the one at the top - but how detailed are the division of species...?

Note that only land dwelling mammals are taken into account - thus no whales. It is not clear as to where, for instance, seals, sea lions and walruses belong -  although they could belong to land mammals.

All other types of animals are not included. For instance, the weight of insects would outweigh us by far. Although not as much as the bacteria mentioned in the title text - they outweigh us 1000:1.

And that is without counting the part of our body weight that consist of bacteria: Several pounds. A fact that most people would properly like to ignore - which is a good reason to mention it here. These pounds are already counted as part of the total human weight.

The comic references the book [http://vaclavsmil.com/the-earths-biosphere-evolution-dynamics-and-change/ The Earth's Biosphere: Evolution, Dynamics, and Change] by {{W|Vaclav Smil}} as the source for most of the data - although a few other sources has also been used. These other sources are not referenced.

==Table of the block sizes==

*The table ranks each of the groups of blocks from 1 to 22 according to the size of the group = the number of blocks. # Blocks thus equals weight of the group in million tons = billion kg.
*There is  total of 1256 blocks representing 1.256 billion tons. 
**358 million tons of humans
**864 million tons of mammal pets and livestock
**34 million tons of wild land dwelling mammals

:Feel free to enter a comment on the groups especially those that are not already identified.

:The population should only be be stated (in millions) if it can found through references - the XKCD average weight (in kg) is then given from the number of blocks in the group.
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
|-
! Rank
! # Blocks
! Type
! Text
!Population (millions)
!XKCD weight (kg)
!Notes/comments
|-
! 1
! 520
! Pets/Livestock
! Cattle
! 1000
! 520
! They only outweighs us by weight - not by numbers - there has been a stable [http://www.statista.com/statistics/263979/global-cattle-population-since-1990/ population] of about {{W|List of even-toed ungulates by population|1 billion cattle}} since 2007.
|-
! 2
! 358
! Humans
! 
! 7200
! 49,7
! According to this [http://www.worldometers.info/world-population/ population counter] there are more than 7.2 billion people in the world today (as of march 2014).
|-
! 3
! 135
! Pets/Livestock
! Sheep
! 1000
! 135
!There is about {{W|List of even-toed ungulates by population|1 billion sheep}} according to wikipedia. The {{W|Domestic_sheep#Description_and_evolution|average sheep}} weight of 135 kg seems highly exaggerated as only the rams can weigh more then that.
|-
! 4
! 90
! Pets/Livestock
! Pigs
! 1000/2100?
! 90/43?
! According to the Wikipedia the {{W|Pig#Distribution_and_evolution|population of pigs}} is about {{W|List of even-toed ungulates by population|1 billion}}. According to the [http://apps.fas.usda.gov/psdonline/psdReport.aspx?hidReportRetrievalName=Swine+Summary+Selected+Countries&hidReportRetrievalID=1649&hidReportRetrievalTemplateID=7 2nd reference] given for this in the wiki article, there is, however, 1.3 billions, and then 0.8 billion more (probably piglets) for a total of 2.1 billion? The piglets will not weigh much though.
|-
! 5
! 39
! Pets/Livestock
! Goats
! 864
! 45
! The {{W|Goat#Worldwide_goat_population_statistics|goat popultaion}} can be summed up to 864 million from the wiki page. According to this list there are {{W|List of even-toed ungulates by population|850 million goats}}.
|-
! 6
! 29
! Pets/Livestock
! Horses
! 58
! 500
! According to Wikipedia there is a population of {{W|List of odd-toed ungulates by population|58 million}} horses. Horses can {{W|Horse#Size_and_measurement|weigh from 400-1000 kg}}. There are probably not that many foals compared to adults, as for instance for cattle and pigs.
|-
! 7
! 13
! Pets/Livestock
! 
!
!
!
|-
! 8
! 10
! Wild animals
! 
!
!
! The largest grouping of wild animals, less than 1/50 of the weight of cattle - although representing almost a third of all the wild land mammals.
|-
! 9
! 8
! Pets/Livestock
! 
!
!
!
|-
! T10
! 7
! Pets/Livestock
! 
!
!
!
|-
! T10
! 7
! Pets/Livestock
! 
!
!
!
|-
! T10
! 7
! Wild animals
! 
!
!
!
|-
! 13
! 6
! Pets/Livestock
! 
!
!
!
|-
! T14
! 5
! Pets/Livestock
! 
!
!
!
|-
! T14
! 5
! Wild animals
! 
!
!
!
|-
! 16
! 4
! Wild animals
! 
!
!
!
|-
! T17
! 3
! Pets/Livestock
! 
!
!
!
|-
! T17
! 3
! Wild animals
! 
!
!
!
|-
! T19
! 2
! Pets/Livestock
! 
!
!
!
|-
! T19
! 2
! Wild animals
! 
!
!
!
|-
! T19
! 2
! Wild animals
! 
!
!
!
|-
! 22
! 1
! Wild animals
! Elephants
!
!
! The only wild animal to be singled out with text - also the heaviest land dwelling animal - but still only take up one block.
|-

|}

==Transcript==
{{incomplete transcript}}
:Earth's Land Mammals by weight

:[After a block to indicate the size of each block:] = 1,000,000 tons

:[Dark gray block:] Humans [Light gray block:] Our pets and livestock [Green block:] Wild animals

:[The rest of the comic consist of blocks representing the weight of mammals. Some of the blocks are labeled:]
:Cattle 
:Pigs
:Goats
:Sheep
:Elephants
:Horses

:[Bottom text:]
:Data from Vaclav Smil's The Earth's Biosphere: Evolution, Dynamics, and Change, Plus a Few Other Sources

{{comic discussion}}