Every AP Environmental Science Practice Test Available

Every AP Environmental Science Practice Test Available SAT / ACT Prep Online Guides and Tips Are you preparing for the Environmental Science AP exam? One of the best ways to study for the test and figure out how well you’re doing is to take practice tests.Taking practice tests lets you see what kind of questions you’ll be asked on the exam, and they can help you figure out which subjects or types of questions you struggle with and need to review more.Finding practice tests can be time-consuming, and, unfortunately, not all practice tests are created equally. Luckily, we’re here to help. In this guide, I’ll provide links to all theAP Environmental Science practice tests available, point out which ones are the highest quality, and explain how you should be using them. Official AP Environmental Science Practice Exams Official practice materials, those developed by the College Board, are the best to use when preparing for an AP exam.This is because, since the practice materials are created by the same organization that develops the real AP test, you can be sure they’ll accurately represent the test and give you the best idea of what the real AP exam will cover. Unfortunately, the College Board doesn’t often like to release a ton of practice material, particularly multiple-choice questions (because they often reuse these for multiple exams). However, there are still official review materialsyou can use which I've separated into three categories. Complete Exams The College Board has released one completeAP Environmental Science practice test, from 1998. Complete 1998 AP Environmental Science exam This test is not super recent, but becauseAP Enviro hasn’t undergone any significant changes since then, it’s still useful and will give you a great idea of what the real exam will be like. This test also contains answers to all the questions, as well as scoring guidelines and sample responses for the free-response questions. Be aware though that, although the questions are still similar, grading guidelines have changed. As a result, the College Board has released a document with updated scoring guidelines for the free-response questions so you can get a more accurate idea of how questions are scored and what your rough score on the exam would be. Multiple-Choice Questions Besides the single complete released practice test, the only place to find official multiple-choice questions for AP Environmental Science is in the Course Description for the class. Beginning on page 12 of the document, you’ll find 17 multiple-choice questions. While this isn’t anywhere close to what you’ll see on the real exam (the actual AP test will have 100 questions), it’ll give you an idea of the topics the exam will cover and how questions will be worded. Free-Response Questions Luckily, there are tons of official free-response questions available for you to study and practice with. The College Board has released previous free-response questions from 1999-2017. Free-response questions 1999-2017 With four free-response questions included on the test each year, that means you have access to 68 official free-response questions! These questions each include scoring guidelines and sample responses so you can get an idea of what the graders were looking for. Possible Other Source: Your Teacher Your AP Environmental Science teacher may also have access to some additional official practice questions that you can use. Teachers are sometimes able to purchase official practice questions from the College Board which students don’t have access to. Now, your teacher may have chosen not to do this, or they may be saving those questions for class exams, but if you’re looking for more official practice materials, you may want to take a chance and ask them. Official practice tests won't come with a seal, but you can be sure they're the highest-qualitypracticematerials out there. Free Unofficial AP Environmental Science Practice Tests You have to be a bit warier when using unofficial practice materials because some of them don’t do a very good job of replicating what topics the AP test covers or how they word their questions. However, there are many that can still be very helpful. For each of the resources below, I’ll explain what material they include and how closely it matches the real AP Environmental Science exam. Barron’s Barron’s has created a high-quality, complete practice exam (with 100 multiple-choice and four free-response questions, just like the actual AP test). This test does a good job of replicating actual AP questions, and it also includes in-depth answer explanations for each question, including sample responses for free-response questions. You can take the test in timed or untimed mode.This is a particularly helpful resource that you should use wisely. (See below for how you should be using this and other resources.) Varsity Tutors Varsity Tutors has a complete multiple-choice section (100 questions). The test is timed and automatically graded for you. While it doesn’t include free-response questions, themultiple-choice questions are similar to those you’ll see on the AP exam.You can combine these questions with a set of official free-response questions and made a complete practice test. If you’d like to practice a specific topic, they also have 148 practice quizzes of varying difficulty for AP Environmental Science, however; the topics are broken down into such specific categories that many quizzes have only 1-2 questions, which can make it tedious to move from one very short quiz to the next.The quizzes can be helpful for more focused studying, but, in general, the complete diagnostic test is the best resource from this site. McGraw-Hill McGraw-Hill offers a 25-question AP Environmental Science practice quiz. This is shorter than many other practice questions and, additionally, the quiz is also untimed. However, the questions are generally well-written, so it’s still a good resource to use. Environmental Science Textbook Quizzes This site includes 20-question quizzes for each of the 25 chapters of the Environmental Science textbook chapters. To select a quiz, choose a chapter from the left-hand side of the page, then choose â€Å"Practice Quiz† on the new page.These quizzes are fairly surface-level, but they can help you study specific topics or prepare for in-class exams, even if you don’t use Environmental Science as your textbook.One frustrating thing is that you’ll have to click on each chapter individually to see what areasit covers if you’re looking to study a particular topic. ProProfs This is an -question multiple-choice quiz. This is quite a short quiz and, strangely, it provides definitions for some keywords you should already know, but it might be helpful if you want a quick study session. High School Test Prep This quiz contains 15 multiple-choice questions. Like ProProfs, its questions are more basic than the majority of those on the actual AP exam will be, but you still may find it useful to try out. Paid Unofficial AP Environmental Science Practice Tests These next resources will cost you a bit of money to use. Shmoop For people who pay its subscription free, Shmoop offers three full-length AP Environmental Science exams as well as a diagnostic test.Paying Shmoop’s fee of $24.68 a month gets you access to these practice tests as well as practice material for a wide variety of other tests forthe ACT, SAT, and other AP exams. Albert Albert has multiple-choice quizzes for each of the seven main ideas of the course. The quizzes are categorized by difficulty, are not timed, and will immediately let you know if you have answered correctly.While some of the questions are free (you'll need to set up an account), you won’t be able to see what the correct answer is if you answered incorrectly or answer any hard-level difficulty questions unless you pay $25 for full access. Full access gives you access to over 200 multiple-choice questions. As a whole, I found these questions to be more basic than actual AP questions.They focused primarily on definitions and basic factsand didn’t emphasize making connections between different topics as much as the real exam does. Review Books Another place to find practice tests is in AP Environmental Science Review books. Most review books contain 1-2 practice tests. These exams can vary in terms of quality, but, in general, Princeton Review and Barron’s are pretty safe bets when it comes to quality. Before you purchase a review book, you should read reviews online or ask students who have previously used the book how well they felt it prepared them for the exam. How to Use AP Environmental Science Practice Tests Now that you know where to find all those practice tests, how should you use them? Taking random tests haphazardly won’t improve your score much, if at all, so follow these guidelines to know which practice materials you should usewhen. First Semester First semester, you’re still learning most of the content you need to know for the exam, so taking a full-length practice exam won’t be very helpful because your score will likely be low since you haven’t covered certain topics yet. During this semester, focus on taking official free-response questions (you can look through them to find ones that focus on information you’ve already covered) and unofficial quizzes that focus on specific content areas (the Environmental Science and Albert quizzes are good places to start). Be sure to start your studying early (by the middle of first semester) and regularly review throughout the year. Doing regular review will help you stay on top of the material, be prepared for class exams, and make reviewing for the final AP test much less overwhelming in the spring.You may also want to consider buying a review book this semester; many of them have practice questions after each chapter so you can see how well you’ve learned the material. Second Semester Second semester is when you should begin really focusing on preparing for the AP exam.At this point, you should have learned the majority of information you need to know for the exam, so you can begin taking full-length practice tests. I recommended beginning with the Barron’s practice test. Take this test under realistic testing conditions (timed and in a quiet room). After you’ve completed it, review how well you did (follow their guidelines for grading your free-response questions). Your score on this test will help you know how well you’re doing and how much studying you need in order to meet your target score. If you’re close to the score you want, you may only need to do light review, but if you’re two points away or more, you’ll likely have to put in some significant time to meet your goal. After taking and scoring your first full-length practice test, look to see where you got questions wrong. The primary reason for taking practice tests is to find where your weaknesses are and then improve in those areas. Don’t just immediately move on to your next practice test, spend time strengthening areas you need to improve on. Perhaps you need to learn how to complete your essays faster, or you realized you really don’t know anything about the nitrogen cycle. Get these gaps taken care of before you take another practice test, otherwise; you won’t see your scores improve.After you feel you’ve reviewed sufficiently, take another practice exam, either the official released test or Varsity Tutors’ multiple-choice section with official free-response questions added to it. Here’s a brief recap of the process you should be following: Take and score your first practice exam (4 hours) Evaluate your mistakes (1.5 hours) Improve your weak areas by doing focused content study and completing practice problems (2.5 hours) Take and score a second practice exam (4 hours) Repeat the steps above as often as you need to in order to make sure you’ve eliminated all your weaknesses for the AP exam and are ready when it comes time to test day. Conclusion AP Environmental Science has the lowest average AP score of any exam. If you want to beat the odds, taking practice tests is one of the best ways to improve your chances of earning a high score.While official practice materials give you the most accurate idea of what will be on the real AP exam, there are high-quality unofficial practice tests out there as well. During your first semester in the class, you should use practice tests to get yourself familiar with the free-response questions and solidify your knowledge of specific topic areas.Second semester is when you can begin taking full-length practice exams toget an idea of how well you’re doing and where you need to improve. What's Next? The free-response sectionistypically the hardest part of the AP Enviro exam. Check outthis guide to learn more about what it'llcover and how to get a high score. Need help starting or continuing your review for AP Enviro? We have acomplete guide to reviewing for the AP Environmental Science exam that'll walk you through each step you need to follow. Wondering which other AP classes you should be taking? Learn how to plan out your futureAP classesby reading this guide. Want to improve your SAT score by 160 points or your ACT score by 4 points?We've written a guide for each test about the top 5 strategies you must be using to have a shot at improving your score. Download it for free now:

First Meditation by Rene Descartes Essay Example | Topics and Well Written Essays - 750 words

First Meditation by Rene Descartes - Essay Example Descartes begins ‘First Meditation’ or ‘On what can be called into Doubt’ by introducing his first proposition that everything he knows, i.e. everything that we know, must be put to the test as they may not exactly be what is real. This is suggesting that the very foundation on which he based everything that he knows must be shattered to truly come up with a conclusion on matters of self-assessment verifiable accuracy. Thus he begins, â€Å"Some years ago I was struck by how many false things I had believed, and by how doubtful was the structure of beliefs that I had based on them† (p. 1). From here he traversed a self-contemplation that was unforgiving in looking at the most minute details to see the logical sequencing on how his perceptions came to be. It suggests going back to the beginning and doing away with all of his opinions to look at the core of his philosophy. Descartes professed that everything is false with clear and ardent belief that th ey are so. He provides that some reason, not altogether significant reason but only an inkling, to tilt the scales over to doubt is an unmistakable occasion for doubt. The foundations are the key in being able to comprehend whether or not there is room for doubt as going at each opinion one by one to look for fallacy would be tedious and next to impossible. When this central aspect is magnified then its analysis becomes possible. The vital attribute of the ‘First Meditation’ is the conversation-like format that is meant to be an almost question and answer type of reading between ‘Hopeful’ and ‘Doubtful.’ The first proposition is a direct interpretation of Aristotelian philosophy on the importance of the senses in our accumulation of knowledge and beliefs. The ‘Hopeful’ dialogue supposes that facts that are perceived by the senses cannot be denied such as the simple position of sitting, the bedtime clothing, the warmth of a fireplac e and the act of gripping a paper. To sustain doubt over such factors such as being in one’s body would be analogous to being mad.  

Case study Example | Topics and Well Written Essays - 1000 words - 34

Case Study Example Plants in Egypt and Trinidad (Atlas and Titan) are worked as joint endeavors with Methanex holding basic interest of 60% and 63.1%, individually. The paper seeks to carry out a comprehensive analysis of the company’s SWOT analysis before the year 2013. In addition, the paper will discuss the key recommendations on how to solve the issues both qualitatively and quantitatively (Methanex, n.d.). Some of the major issues affecting the company include holding a large amount of Assets (PPE) sitting unused due to political instability in Chile and Egypt leading to wastages. Notably, these wastes constitute to close to $1.87 B in initial investment costs that could be put to constructive use. In addition, the company lacks diversification and is completely dependent on the sale of Methanol making it not competitively effective. Besides, the company has not fully taken advantage of economies of scope since almost all of its competitors produce other materials (Methanex, n.d.). Methanol in its pure form cannot be directly used since companies buy from Methanex to produce other materials. The replacement cost of assets are more than the market value of the company (2/3 cost). This implies that if the company goes under, they could not sell assets to cover all the cost. Another major challenge that the company faces is high operational cost (Zacks.com, 2014). In fact, 80% of cash co sts go to purchase of natural gas and energy use costs hence increasing the operational cost (Arslan & Er, 2008). Its greatest contender (MHTL), could conceivably make them bankrupt in Trinidad (where the vast majority of Methanexs yield is produced) The biggest utilization for methanol, formaldehyde, has had terrible attention in the U.S. in view of conceivable negative wellbeing impacts identified with presentation (Leukemia, numerous myeloma, Hodgkins). High purchaser power- methanol expenses represent a little divide of what

Theories On Second Language Acquisition English Language Essay

Theories On Second Language Acquisition English Language Essay Several studies have revealed how dynamics in cultural identity influenced the learning of a second language (Graham Brown, 1996; McCarthy, Giardina, Harewood, Park, 2003). The process of language learning itself is socially and culturally constructed (Norton-Piece Toohey, 2001). How social formations, individual identities, and interpretations belonging to a particular culture is crucial to the development of language. Culture As defined by Brown (2007), culture is the ideas, customs, skills, arts, and tools that characterize a given group of people in a given period of time (p. 380). A more comprehensive definition of culture developed by DÃ ­az-Rico and Weed (2006) views it as: The explicit and implicit patterns for living, the dynamic system of commonly agreed upon symbols and meanings, knowledge, belief, art, morals, law, customs, behaviors, traditions, and/or habits that are shared and make up the total way of life of a people, as negotiated by individuals in the process of constructing a personal identity. (p. 233) This definition highlights the fact that culture is a dynamic, instead of static process and is neither something to be memorized nor a program that can be encoded to dictate behavior. The process of learning a new language while being immersed in a new culture involves cultural conflict and reconciliation of that conflict in order to come to terms with the host culture. Learning a second language even demands of an individual to take on a new identity (Guiora, 1995, p. 145). As a consequence, ones basic sense of self and confidence in ones abilities are challenged in this process of developing a new identity to cope with the acquisition of a new language. This process is called acculturation, generally referred to as the act of adjusting to a new culture. Acculturation There have been different models to explain the role of acculturation in the acquisition of a second language. Many authors have suggested that acculturation need not mean the eradiction of the old culture itself. Acculturation is adapt[ing] to a second culture without necessarily giving up ones first culture (Diaz-Weed, 2007, p. 246). This is contrary to the view that acculturation is synonymous to assimilation (total absorption into the new culture) or accommodation (mutual adjustment of cultures). Absorbing particular domains of a new society does not mean total surrender of the old or the zero-sum trade off (Berry, 1997, p. 34). Degrees of acculturation could be in four levels: integration (positive relationship to new and old), assimilation (relinquishing old, embracing new), segregation (retaining old, rejecting new), and marginalization (relinquishing old and new) (Berry, 1997). Theories on Second Language Acquisition The earliest research on second language acquisition (SLA) have been motivation studies which hypothesized that motivation is the fundamental factor toward SLA. Founded on the work of Robert Gardner and Wallace Lambert, the relationship of motivation and SLA have been helpful in understanding how the social and cultural environments of L2 learners shape their attitudes and motivations toward the L2, its culture, and L2 speakers (Gardner, 1979, 1980). These studies have pointed out that as a consequence, learners display behaviors which could either promote or impede their SLA outcomes (Gardner, 1979). Motivation for learning an L2 is divided by Gardner into two components: instrumental and integrative motivation. Instrumental motivation concerns an individuals primary concern for linguistic growth, apart from social goals in SLA (Gardner, 1979, 1983, 1988; Gardner Lambert, 1959, 1972). Integrative motivation refers to an individuals willingness and interest in promoting L2 acquisiti on through social interactions with members of the L2 group (Gardner Lambert, 1959, 1972; Gardner, 1979, 1983, 1988). Instrumental motivation is suggested by Gardner and Lambert to have a primary role in learning of the L2, while integrative motivation is depicted playing a lesser, supporting role (Gardner, 1979, 1983, 1988; Gardner, Tremblay Masgoret, 1997; Gardner Lambert, 1972). Many theorists have criticized motivation studies as not sufficiently explaining the role of acculturation in SLA. According to Brown (1980, 2007), second language learners are optimally suited to learn the Culture and SLA second language when certain conditions of acculturation are met. Specifically, the optimal period is when learners are in the third stage of acculturation and also see themselves as outside of both their native culture and the second culture. Schumann (1986) claims that acculturation, or the integration of the L2 learner into the target linguistic community, is not a direct cause of second language acquisition (SLA), but rather it is the first in a chain of factors which results in natural SLA. He proposes that acculturation as a remote cause brings the learner into contact with TL-speakers and verbal interaction with those speakers as a proximate cause brings about the negotiation of appropriate input which then operates as the immediate cause of language acquisition (p. 385). Acculturation (made up of social and affective variables) is the causal varibale of SLA. That is, if learners acculturate, they will learn; if learners do not acculturate, they will not learn. Acculturation initiates a chain reaction including contact in the middle and acquisition as its outcome. Schumanns (1986) acculturation model includes seven social variables (1. social dominance, 2. assimilation, preservation, and adaptation, 3. enclosure, 4. cohesiveness and size, 5. congruence, 6. attitude, 7. intended length of residence) and four affective variables (1. language shock, 2. culture shock, 3. ego permeability, and 4. motivation) which presumably affect the quantity and quality of contact that second language learners have with the target language community, thus affecting SLA. Schumann argues that the degree to which a learner acculturates to the TL group will control the degree to which he acquires the second language (Schumann, 1978, p. 34), but he makes his claim only for the context of natural SLA, i.e., where learning takes place in the environment where the L2 is spoken and without direct language instruction (1986, p. 385). Language proficiency and acculturation There has been a dearth in empirical studies that examined the impact of a learners degree of acculturation on language proficiency or acquisition. Extant studies have however suggested that acculturation and language acquisition have a positive relationship. Acculturation is a more significant determinant in language proficiency than motivation or attitudes, as evidenced by Clements (1986) study. Clement (1986) showed how the interplay of motivation, individual attitudes and degree of acculturation result to SLA proficiency in quantitative cross-sectional study. In a correlational research conducted in a bilingual Canadian university, students were asked to fill up questionnaires that assessed ethnolinguistic vitality, motivation, and attitudes. Moreover, interviews were conducted among respondents to evaluate their proficiency in spoken English as a second language. Minority group members exhibited more self-confidence in their skill of speaking English as a second language and were also judged to be more proficient than members of the majority group. The level of acculturation measured by the frequency of L2 use and frequency of contact with L2 speakers was revealed to be functional in language proficiency. Motivation and attitudes tow ard L2 speakers, and L2 culture were not significantly correlated to language proficiency. Friendships and immersion with native English-speaking people is also important in cultivating SLA and proficiency. As shown in Graham and Browns (1996) study in a bilingual community in Mexico, the difference in proficiency among native Spanish speakers in speaking English could be a result of the varying levels of their acculturation to native English speakers. Using Schumanns (1986) acculturation model and variables, the degree of acculturation was measured among native Spanish-speaking households in Colonia Juarez town. To measure language proficiency, an oral proficiency interview was conducted. Native-like English proficiency among native Spanish speakers was attained only by those enrolled in bilingual schools. Their enrollment in the schools proved favorable to their SLA. Moreover, they developed more positive perceptions about the English-speaking community and developed more intimate friendships with their English-speaking peers (Graham Brown, 1996). Degree of acculturation, age, and marital status are also important factors in language proficiency. Lee (2005) investigated the relationship of English proficiency and degree of acculturation in terms of U.S. media consumption. The results revealed that the use of Korean language over the Internet negatively correlated with acculturation. Those that did not use English when consuming and participating in Internet-based communication were less proficient in speaking English than those that used English frequently. Moreover, younger and single Koreans were more proficient in speaking English than older and married Koreans due to their higher levels of U.S. media consumption (Lee, 2005). Lees study is consistent with the findings from Jiang et al. (2009) which found that greater degrees of immersion in American society leads to higher proficiency in the English language. Jiang et al. (2009) studied acculturation and Enlighs proficiency by studying an older Chinese-English population. Correlational analyses revealed a strong relationship between the degree of immersion in the dominant society and proficiency in oral English. Nevertheless, while speaking proficiency was found to be correlated with acculturation, accents were not.

Essay --

Income inequality can be defined as the difference of distribution of assets, wealth, and income between the populations. The term income inequality refers to the inequality among persons within a society. The topic is commonly debated, and the liberties and rights of people are often brought into the debate being made. In America, it has been said that â€Å"The 400 richest people in the United States have more wealth than the bottom 150 million put together† leading the reader to believe there is a huge inequality problem that is only growing wider. There is no doubt that the income gap in America is growing, with the middle class taking home 9% less than they had in 1999, but I feel that the government does not have the obligation to lessen the gap between rich and poor. There is no doubt that the economic ladder is growing farther and farther apart and the rungs of this ladder are becoming harder and harder to climb, however, the government does not hold the obligation to lessen the gap. The UN’s Universal Declaration of Human Rights states that equality and liberty will be protected...

Business Documents Essay

English editing (or re-writing) can cause discomfort, because it often reveals hidden weaknesses in the original document. But companies willing to accept the treatment and put in any work necessary will produce a document that shines. By turning existing, long-winded and inaccessible text into clear writing, plain English can shine an uncomfortably bright light on flaws in the original content that would otherwise remain unnoticed. The reality is that in many businesses, a lot of very talented and experienced professionals can spend an awful lot of time doing fantastic research and work only to produce a document that fails dismally to do them credit. Why do all that work if the final report, which may be so critical, simply isn’t fit for purpose? Companies and organisations are increasingly recognising that the reports they produce need to read clearly. They recognise that the text needs to be in plain English. The author is not the reader. Putting the text through the plain English editing process can polish text until it shines with clarity. That’s great if the bones of the report, the facts and figures and findings etc, are already solid. But sometimes, the editing process itself can throw up uncomfortable questions. It reveals flaws in original document, highlights waffle, questions in-house jargon, and draws attention to unsubstantiated claims. And that’s when a businesses’ true grit shows. ‘Your editing highlighted the fact that there were holes in just about every paragraph,’ one client told me. ‘The plain English showed us just how many gaps we need to fill before we can send the report to our client. ’

What (or Who) Killed the Planets Big Mammals

Megafaunal extinctions refers to the documented die-off of large-bodied mammals (megafauna) from all over our planet at the end of the last ice age, at about the same time as the human colonization of the last, farthest-flung regions out of Africa. The mass extinctions were neither synchronous nor universal, and the reasons proffered by researchers for those extinctions include (but are not limited to) climate change and human intervention. Key Takeaways: Megafaunal Extinctions Megafaunal extinctions occur when a preponderance of large-bodied mammals seem to die off at the same time.There have been six megafaunal extinctions on our planet during the Late PleistoceneThe most recent fell between 18,000–11,000 years ago in South America, 30,000–14,000 in North America, and 50,000–32,000 years ago in Australia.  These periods occur when the continents were first inhabited by humans, and when climate changes were occurring.It seems likely that rather than being caused by a particular occurrence, all three things (megafaunal extinctions, human colonization, and climate change) acted together to bring environmental change to the continents.   The Late Pleistocene megafaunal extinctions occurred during the Last Glacial–Interglacial Transition (LGIT), essentially the last 130,000 years, and it affected mammals, birds, and reptiles. There have been other, much earlier mass extinctions, impacting animals and plants alike. The five largest mass extinction events in the past 500 million years (mya) occurred at the end of the Ordovician (443 ma), the Late Devonian (375–360 mya), the end of the Permian (252 mya), the end of the Triassic (201 mya) and the end of the Cretaceous (66 mya). Pleistocene Era Extinctions Before early modern humans left Africa to colonize the rest of the world, all of the continents were already populated by a large and diverse animal population, including our hominid cousins, Neanderthals, Denisovans, and Homo erectus. Animals with body weights greater than 100 pounds (45 kilograms), called megafauna, were abundant. Extinct elephant, horse, emu, wolves, hippos: the fauna varied with the continent, but most of them were plant-eaters, with few predator species. Almost all of these megafauna species are now extinct; almost all of the extinctions occurred around the time of the colonization of those regions by early modern humans. A replica statue of the extinct Mylodon ground sloth which inhabited the south of the Chilean and Argentinian Patagonia, inside a cave in the Torres del Paine national park which was home to the pre-historic creature. Germà ¡n Vogel / Getty Images Before migrating far from Africa, early modern humans and Neanderthals co-existed with megafauna in Africa and Eurasia for several tens of thousands of years. At the time, most of the planet was in steppe or grassland ecosystems, maintained by megaherbivores, massive vegetarians that impeded the colonization of trees, trampled and consumed saplings, and cleared and broke down the organic matter. Seasonal aridity influenced the availability of rangelands, and climate change involving increases in moisture is documented for the late Pleistocene, which is believed to have exerted extinction pressure on megafaunal rangeland grazers by altering, fragmenting and in some cases replacing the steppes with forests. Climate change, migration of humans, extinction of megafauna: which came first? Which Came first? Despite what you may have read, it is not clear which of these forces—climate change, human migration, and megafaunal extinctions—caused the others, and it is very likely that the three forces worked together to re-sculpt the planet. When our earth became colder, the vegetation changed, and animals that did not adapt rapidly died out. Climate change may well have driven human migrations. People moving into new territories as new predators might have had negative effects on the existing fauna, through overkill of a particularly easy animal prey, or the spread of new diseases. But it must be remembered that the loss of the mega-herbivores also drove climate change. Enclosure studies have shown that large-bodied mammals such as elephants suppress woody vegetation, accounting for 80% of woody plant loss. The loss of large numbers of browsing, grazing, and grass-eating mega-mammals certainly led or added to the decrease of open vegetation and habitat mosaics, the increased occurrence of fire, and the decline of co-evolved plants. Long-term effects on seed dispersion continue to affect plant species distributions for thousands of years. This co-occurrence of humans in migration, climate change, and animal die-off is the most recent time in our human history where climate change and human interactions together re-designed the living palette of our planet. Two areas of our planet are the primary focus of the studies of Late Pleistocene megafaunal extinctions: North America and Australia, with some studies continuing in South America and Eurasia. All of these areas were subject to massive changes in temperature, including the variable presence of glacial ice, and plant and animal life; each sustained the arrival of a new predator in the food chain; each saw related decreases and reconfiguration of the available animal and plants. Evidence collected by archaeologists and paleontologists in each of the areas tells a slightly different story. North America Earliest human colonization: 15,000 calendar years ago (cal BP), (pre-Clovis sites)Last glacial maximum: ~30,000–14,000 cal BPYounger Dryas: 12,900–11,550 cal BPImportant sites: Rancho La Brea (California, USA), many Clovis and pre-Clovis sites.Die-off range: 15% disappeared during Clovis and the Younger Dryas overlap, 13.8–11.4 cal BPSpecies: ~35, 72% of megafauna, including dire wolf (Canis dirus), coyotes (C. latrans), and saber-toothed cats (Smilodon fatalis); American lion, short-faced bear (Arctodus simus), brown bear (Ursus arctos), scimitar-tooth sabercat (Homotherium serum), and dhole (Cuon alpinus) While the exact date is still under discussion, it is most likely that humans first arrived in North America no later than about 15,000 years ago, and perhaps as long ago as 20,000 years ago, at the end of the last glacial maximum, when entrance into the Americas from Beringia became feasible. The North and South American continents were rapidly colonized, with populations settled in Chile by 14,500, surely within a few hundred years of the first entry into the Americas. North America lost about 35 genera of mostly large animals during the Late Pleistocene, accounting for perhaps 50% of all mammal species larger than 70 lbs (32 kg), and all species larger than 2,200 lbs (1,000 kg). The ground sloth, American lion, dire wolf, and short-faced bear, wooly mammoth, mastodon and Glyptotherium (a large bodied armadillo) all disappeared. At the same time, 19 genera of birds disappeared; and some animals and birds made radical changes in their habitats, permanently changing their migration patterns. Based on pollen studies, plant distributions also saw a radical change primarily between 13,000 to 10,000 calendar years ago (cal BP). Between 15,000 and 10,000 years ago, biomass burning gradually increased, particularly at the movements of rapid climate change at 13.9, 13.2, and 11.7 thousand years ago. These changes are not currently identified with specific changes in human population density or with the timing of the megafaunal extinction, but that doesnt necessarily mean that they are unrelated—the effects of the loss of large-bodied mammals on vegetation are very long-lasting. Australian Evidence Earliest human colonization: 45,000–50,000 cal BPImportant sites: Darling Downs, Kings Creek, Lynchs Crater (all in Queensland); Mt Cripps and Mowbray Swamp (Tasmania), Cuddie Springs and Lake Mungo (New South Wales)Die-off range: 122,000–7,000 years ago; at least 14 Mammalian genera and 88 species between 50,000–32,000 cal BPSpecies: Procoptodon (giant short-faced kangaroo), Genyornis newtoni, Zygomaturus, Protemnodon, sthenurine kangaroos and T. carnifex In Australia, several studies of megafaunal extinctions have been conducted of late, but the results of them are contradictory and conclusions must be considered controversial today. One difficulty with the evidence is that the human entrada into Australia occurred so much longer ago than that of the Americas. Most scholars agree that humans reached the Australian continent at least as long as 50,000 years ago; but evidence is sparse, and radiocarbon dating ineffective for dates older than 50,000 years old. Genyornis newtoni, Zygomaturus, Protemnodon, sthenurine kangaroos and T. carnifex all disappeared at or shortly after the human occupation of the Australian mainland. Twenty or more genera of giant marsupials, monotremes, birds, and reptiles were likely wiped out due to the direct intervention of human populations since they can find no connection to climate change. The local decline in diversity began nearly 75,000 years before human colonization, and thus cannot be the result of human intervention. South America Less scholarly research concerning the mass extinctions in South America has been published, at least in the English-language academic press. However, recent investigations suggest that the extinction intensity and timing varied across the South American continent, beginning in the northern latitudes several thousand years before the human occupation, but becoming more intense and rapid in the southern higher latitudes, after humans arrived. Further, the pace of extinction seems to have accelerated about 1,000 years after the humans arrived, coinciding with regional cold reversals, the South American equivalent of Younger Dryas. Some scholars have noted patterns of stadial/interstadial differences between North and South America, and have concluded that although there is no evidence for the blitzkrieg model—that is to say, mass-killing by humans--the human presence in combination with the rapid expansion of forests and environmental changes seems to have led to the collapse of the megafaunal ecosystem within a few hundred years. Earliest human colonization: 14,500 cal BP (Monte Verde, Chile)Last glacial maximum: 12,500-11,800 cal BP, in PatagoniaCold Reversal (Roughly equivalent to the Younger Dryas): 15,500-11,800 cal BP (Varies across the continent)Important sites: Lapa da Escrivà ¢nia 5(Brazil), Campo La Borde (Argentina), Monte Verde (Chile), Pedra Pintada (Brazil), Cueva del Milodà ³n, Fells Cave (Patagonia)Die-off: 18,000 to 11,000 cal BPSpecies: 52 genera or 83% of all megafauna; Holmesina, Glyptodon, Haplomastodon, prior to human colonization; Cuvieronius, Gomphotheres, Glossotherium, Equus, Hippidion, Mylodon, Eremotherium and Toxodon about 1,000 years after initial human colonization; Smilodon, Catonyx, Megatherium, and Doedicurus, late Holocene Recently, evidence of the survival of several species of giant ground sloth has been discovered in the West Indies, to as late as 5,000 years ago, coincident with the arrival of humans in the region. Selected Sources Barnosky, Anthony D., et al. Variable Impact of Late-Quaternary Megafaunal Extinction in Causing Ecological State Shifts in North and South America. Proceedings of the National Academy of Sciences 113.4 (2016): 856–61.  DeSantis, Larisa R. G., et al. Dietary Responses of Sahul (Pleistocene Australia–New Guinea) Megafauna to Climate and Environmental Change. Paleobiology 43.2 (2017): 181–95.  Galetti, Mauro, et al. Ecological and Evolutionary Legacy of Megafauna Extinctions. Biological Reviews 93.2 (2018): 845–62.  Metcalf, Jessica L., et al. Synergistic Roles of Climate Warming and Human Occupation in Patagonian Megafaunal Extinctions During the Last Deglaciation. Science Advances 2.6 (2016).  Rabanus-Wallace, M. Timothy, et al. Megafaunal Isotopes Reveal Role of Increased Moisture on Rangeland During Late Pleistocene Extinctions. Nature Ecology Evolution 1 (2017): 0125.  Tà ³th, Anikà ³ B., et al. Reorganization of Surviving Mammal Communitie s after the End-Pleistocene Megafaunal Extinction. Science 365.6459 (2019): 1305–08.  van der Kaars, Sander, et al. Humans Rather Than Climate the Primary Cause of Pleistocene Megafaunal Extinction in Australia. Nature Communications 8 (2017): 14142.