Question

Measurements of the extent of amino-acid decomposition in fragments of eggshell found at archaeological sites in such places as southern Africa can be used to obtain accurate dates for sites up to 200,000 years old. Because the decomposition is slower in cool climates, the technique can be used to obtain accurate dates for sites almost a million years old in cooler regions. The information above provides the most support for which one of the following conclusions? (A) The oldest archaeological sites are not in southern Africa, but rather in cooler regions of the world. (B) The amino-acid decomposition that enables eggshells to be used in dating does not take place in other organic matter found at ancient archacological sites. (C) If the site being dated has been subject to large unsuspected climatic fluctuations during the time the eggshell has been at the site, application of the technique is less likely to yield accurate results. (D) After 200,000 years in a cool climate, less than one-fifth of the amino acids in a fragment of eggshell that would provide material for dating with the technique will have decomposed and will thus no longer be suitable for examination by the technique. (E) Fragments of eggshell are more likely to be found at ancient archacological sites in warm regions of the world than at such sites in cooler regions.

Short answer

Conclusion (C) is best supported.

Step-by-step solution

Understand the Context

The exercise focuses on using amino-acid decomposition in eggshell fragments found at archaeological sites to determine the age of the site. The decomposition rate varies with climate, being slower in cooler climates, which allows for dating older sites in these regions.

Analyze What is Supported

The text supports conclusions about the effectiveness and limitations of this dating technique based on climate. Key points include that decomposition happens slower in cooler climates, thus allowing for more extended dating periods.

Evaluate Each Option

Consider each option to determine which is best supported by the given information: (A) claims sites are in cooler regions, but this isn't directly supported by decomposition rates. (B) suggests decomposition does not occur in other materials, which is not discussed. (C) mentions the effect of climate changes on accuracy, which aligns with the climate factor in decomposition. (D) involves specific data not given in the passage. (E) suggests frequency of eggshells in regions, which isn't mentioned.

Select the Best Supported Conclusion

From all options, (C) is best supported since it directly relates to the impact of climate on the technique's accuracy, aligning with the information provided. Climate fluctuations could interfere with the expected decomposition rate, affecting the dating's accuracy.

Key concepts

Archaeological dating techniques

Archaeological dating techniques are vital tools that help scientists and researchers understand the timeline of historical sites and artifacts. Among these, amino-acid decomposition dating stands out due to its ability to function over extensive periods. This technique involves studying the deterioration of amino acids within fossils and organic materials, like eggshells, discovered at archaeological sites. The decomposition process helps determine the age of the specimens.
Amino-acid decomposition dating is particularly effective in environments where traditional carbon dating might not succeed, like in sites beyond 40,000-50,000 years old. It's applicable to much older timeframes, sometimes stretching up to a million years, especially in cooler climates where decomposition happens very slowly.
This method offers a unique advantage:

• It provides the ability to date older archaeological sites than some other methods.
• The level of precision remains high when the climate-related changes in decomposition rates are faithfully accounted for.

By incorporating climatic data and understanding the chemistry behind amino-acid changes, researchers can achieve more accurate dating of archaeological sites.

Climate impact on organic matter

Climate plays a crucial role in the decomposition of organic matter, significantly affecting the results of dating techniques. Different climates have varying temperatures and humidity levels, which influence how quickly amino acids break down. In warmer climates, decomposition speeds up, making eggshells more challenging to date accurately over long periods.
Conversely, cooler climates slow the decomposition process, allowing for more extended use of amino-acid decomposition dating techniques. This is why dates tend to be more accurate in cooler regions, sometimes even reaching back almost a million years.
However, if a site has experienced significant climate fluctuations over time, these variations can complicate the dating results.

• For example, an eggshell may have been subject to different temperature and humidity conditions, affecting the decomposition timeline.
• Large climatic shifts introduce uncertainties, potentially disturbing the expected decay patterns of amino acids.

Thus, understanding the historical climate context of the site is crucial for precise archaeological dating.

Eggshells in archaeology

Eggshells are a fascinating yet often overlooked resource in archaeology. Their robustness and chemical stability under certain conditions make them excellent candidates for dating purposes. They offer a strong structural matrix that helps preserve amino acids better over long durations than some other organic materials.
When archaeologists find eggshell fragments at sites, they gain a valuable opportunity to uncover information about both the age of the site and the historical climate. This is because eggshells respond to climatic conditions directly, recording temperature and humidity effects.
Research on eggshells contributes both to dating the site and understanding past environmental conditions.

• They are often used in regions where other organic remains do not survive well.
• Eggshells can reflect dietary and ecological information, offering insights into the lifestyle of past human and animal populations.

In summary, the study of eggshells combines multiple facets of archaeological science, making them valuable tools for understanding ancient life.