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Jacob Cox
Jacob Cox

14 : Footprints PORTABLE

"I feel extremely honored to be able to do this. It's never something I actually thought about when I was watching movies. I never thought my hand and footprints would be sitting right here at Grauman's Chinese Theatre."

14 : Footprints

Bryant told CBS2 at the time that having his handprints and footprints displayed along with of the legends of the movie industry was "right at the top" of his many accomplishments, including helping the Lakers to five NBA championships.

Nucleosome positioning varies between cell types. By deep sequencing cell-free DNA (cfDNA), isolated from circulating blood plasma, we generated maps of genome-wide in vivo nucleosome occupancy and found that short cfDNA fragments harbor footprints of transcription factors. The cfDNA nucleosome occupancies correlate well with the nuclear architecture, gene structure, and expression observed in cells, suggesting that they could inform the cell type of origin. Nucleosome spacing inferred from cfDNA in healthy individuals correlates most strongly with epigenetic features of lymphoid and myeloid cells, consistent with hematopoietic cell death as the normal source of cfDNA. We build on this observation to show how nucleosome footprints can be used to infer cell types contributing to cfDNA in pathological states such as cancer. Since this strategy does not rely on genetic differences to distinguish between contributing tissues, it may enable the noninvasive monitoring of a much broader set of clinical conditions than currently possible.

Fossil hominin footprints preserve data on a remarkably short time scale compared to most other fossil evidence, offering snapshots of organisms in their immediate ecological and behavioral contexts. Here, we report on our excavations and analyses of more than 400 Late Pleistocene human footprints from Engare Sero, Tanzania. The site represents the largest assemblage of footprints currently known from the human fossil record in Africa. Speed estimates show that the trackways reflect both walking and running behaviors. Estimates of group composition suggest that these footprints were made by a mixed-sex and mixed-age group, but one that consisted of mostly adult females. One group of similarly-oriented trackways was attributed to 14 adult females who walked together at the same pace, with only two adult males and one juvenile accompanying them. In the context of modern ethnographic data, we suggest that these trackways may capture a unique snapshot of cooperative and sexually divided foraging behavior in Late Pleistocene humans.

Footprints are often ephemeral but when preserved in the geological record, these ichnofossils can provide unique snapshots of the lives of ancient organisms. Fossil tracks are generated and preserved on far shorter time scales than other common forms of fossil data (e.g., skeletal fossils), leading to a distinct set of hypotheses that can be developed and tested with this form of evidence. In paleoanthropology, researchers have analyzed fossil hominin footprints through a variety of analytical approaches that address a wide range of research questions (many are reviewed by Bennett and Morse1). Perhaps most common are analyses that derive inferences regarding hominin body size and size variation2,3,4, or foot anatomy, foot function and/or locomotion4,5,6,7,8,9,10,11,12,13,14,15,16,17. However, since footprint assemblages typically form on short time scales, these data can also be used to infer group composition and other behaviors of individuals who must have lived on the same landscape at the same time16,18,19,20,21,22,23.

Here, we report on Late Pleistocene human footprints discovered at Engare Sero, Tanzania. While our previous publications focused on the geological context and preservation of this site24,25, we explore the paleoanthropological implications of this remarkable assemblage of more than 400 human footprints. This includes inferences regarding the body sizes, locomotor behaviors, and composition of the group of humans who generated these tracks.

As described above, the Engare Sero footprint surface preserves at least 408 human footprints (Fig. 2). All of the footprints appear to have been produced by barefoot humans, as individual toe impressions are easily distinguishable (Fig. 3). Because of their apparent human-like morphology and their Late Pleistocene age, we have attributed these tracks to Homo sapiens. There are likely many more than 408 tracks preserved at Engare Sero. Finite boundaries exist along three sides of the excavation, where surface sediments have been removed and no additional tracks are visible. However, along the northern boundary of the excavation, several trackways lead directly beneath unexcavated sediments (Fig. 2). Excavation of additional sediments has been halted until a long-term site conservation plan is implemented, as we know the exposed portion of the site is subject to erosion25.

To better understand the potential structure (i.e., composition) of the group of humans that created the Engare Sero footprints, we developed a statistical protocol to determine the likelihood that each trackway sampled an adult or juvenile female or male individual. This analysis required two different comparative datasets. The first of these was the same experimental footprint data set described above, which was used for speed and stature estimation. The second included data from a large sample of 3233 individuals (1652 male, 1581 female, ranging from 2 to 52 years of age), which were collected during two published anthropometric studies42,43 and made available to us. This data set included measurements of foot length for each participant in the study and identified whether each subject was male or female. We note that this anthropometric study did not describe the methods that were used for sex categorization. Sex classifications restricted to only two categories do not appropriately consider biological and anatomical diversity related to sex, and we acknowledge that by employing this comparative data set these limitations will carry over to our fossil analysis.

Next, we sought to develop a method for distinguishing adult versus juvenile feet, this time employing the much larger ontogenetic anthropometric data set. First, we developed sex-specific growth plots for foot length, and visually identified cessations of foot growth at approximately age 14 for females and age 17.8 for males (Fig. S3). All individuals equal in age or older than those sex-specific cutoffs in this sample are considered to have adult feet, and all younger individuals have juvenile feet. These classifications were then used in the process of classifying footprints to age-sex categories.

Ileret, Kenya. 1.5 Ma. They are 97 footprints left by at least 20 Homo erectus individuals, who had a modern foot and stride: a mid-foot arch, straight big toe and heel-to-toe weight transfer. The footprints are indistinguishable from our own.

Happisburgh in Norfolk, UK. 850 ka. Assigned by many authors to Homo antecessor. Previously, the record for the oldest set of footprints in Britain was 7,500 years old, which pales in comparison to the Norfolk find.

White Sands National Park, New Mexico, USA. A group of 60 footprints radiocarbon-dated to 21,000-23,000 years old. Based on stature and walking speed, it appears that most of the footprints in this study come from teenagers and children.

Calvert Island, British Columbia, Canada. 29 footprints along the shoreline of Calvert Island published in 2015. They are believed to be of a man, woman and child. At the base of the footprint track, pieces of preserved wood were radiocarbon dated to c. 13,000 years.

Jeju Island, Korea. More than 100 human footprints and other thousands of horse, elephant, bird and deer fossil tracks left 50,000 years ago. Further studies suggest a more recent dating of between 19-25 ka.

What about the Trachilos footprints (5.7 mya, Crete in Europe)? Even though they were most likely not made by modern humans, I feel like they deserve some mention as the oldest bipedal footprints in the world. _footprints

A carbon footprint (or greenhouse gas footprint) is a "certain amount of gaseous emissions that are relevant to climate change and associated with human production or consumption activities".[2] In some cases, the carbon footprint is expressed as the carbon dioxide equivalent (CO2e) which is meant to sum up the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product.[3] In other cases, only the carbon dioxide emissions are taken into account but not those of other greenhouse gases.[4] Greenhouse gases, including the carbon-containing gases carbon dioxide and methane, can be emitted through the burning of fossil fuels, land clearance, and the production and consumption of food, manufactured goods, materials, wood, roads, buildings, transportation and other services.[5] As well as calculating carbon footprints for whole countries, it is also possible to calculate the footprint of regions, cities, and neighbourhoods.[6]

The concept and name of the carbon footprint was derived from the ecological footprint concept.[2] While carbon footprints are usually reported in tons of emissions (CO2-equivalent) per year, ecological footprints are usually reported in comparison to what the planet can renew. This assesses the number of "earths" that would be required if everyone on the planet consumed resources at the same level as the person calculating their ecological footprint. The carbon footprint is one part of the ecological footprint. Carbon footprints are more focused than ecological footprints since they merely measure emissions of gases that cause climate change into the atmosphere.[citation needed]

The Carbon Trust has worked with UK manufacturers on foods, shirts and detergents, introducing a CO2 label in March 2007. The label is intended to comply with a new British Publicly Available Specification (i.e. not a standard), PAS 2050,[41] and is being actively piloted by The Carbon Trust and various industrial partners.[42] As of August 2012 The Carbon Trust state they have measured 27,000 certifiable product carbon footprints.[43] 041b061a72


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